dwightlooi

It's not a matter of easier or harder. It's a matter of existing refinery infrastructure. When crude oil is fractionally distilled, it produces some natural gas, some gasoline, some kerosene, some diesel and a lot of heavier products like fuel oil, lubricant oil, tar, etc. There is way more of the "heavy" and "thick" stuff than the market has demand for. I mean you may pump gasoline into your car twice week, but you probably change the oil once every 6 months. So, refineries don't stop at fractional distillation. They use a process called "cracking" to break down these heavier products into lighter grades of fuel. In the US, because gasoline is the dominant automotive fuel, refineries are overwhelmingly set up to use catalytic cracking which produces a lot of gasoline, some kerosene and a little diesel. In Europe, hydrocracking is the method of choice because it produces a lot of diesel and kerosene, but significantly less gasoline. The entire refinery infrastructure has evolved to meet the different demands of the regions. This however is not an easy infrastructure to redo in a decade and impossible to change over night.

OK, back to engines... The current 10.7:1 LS3 is already 436/428. With direct injection you are looking at 11.7:1 ~ 12.3:1 compression. That in an of itself is worth about 6% of torque increase across the board. That equates to about 462/454. The only reason I peg it at 470/438 I wanted to limit torque to 438 -- the torque limit of the 6L80 transmission is 439 lb-ft. And, a meaningful way of doing that is to basically give both cams a little advancement. This drops torque slightly, but also shifts the curve to the right making a little more power. I think I am being quite conservative here. The figures assume that there is no improvement in the engine other than adding direct injection and no change in the cam grind only an advancement of the base timing. The only gains come from an increased compression ratio.

I don't think there has been an orchestrated conspiracy, there has just been a huge bias in both media coverage and in terms of people getting on the wrong bandwagon either to further environmental causes, to earn peer support or funding for their research or whatever their motives may be. It is not that all scientists, or an over whelming majority, agree with the global warming hypothesis. It is just that those who do not are being shut up by the media, by politicians and by their peers; denied the forums to present and/or publicize opposing opinion. The whole Global Warming nonsense reached a critical mass and took on a life of its own independent of the science or the facts. For instance, a person with no scientific credentials in climate science, Al Gore, was brought to testify before congress on Global Warming, whereas a professor of Atmospheric Science at MIT like Richard Lindzen was deemed inappropriate or unqualified. In a sense, Global warming, or now that they cannot claim any warming "Climate Change", has become a religion -- a vindictive, witch hunting, dissent suppressing theocracy of sorts. True science should not be a belief system. What makes you think that a milder, less volatile climate is the norm? What makes you think that whatever changes we are seeing in weather patterns is not normal in the context of the history of weather patterns of this planet? In fact, they are all very normal, the planet has been a more violent and volatile place in various periods prior to industrialization and the rise in CO2 concentrations in the air. We are fortunate to have experienced a mild period. That it has come to an end should not surprise. More importantly, one cannot point at Carbon Emissions and say that's the cause because there is no evidence of that. Yes, CO2 is a heat trapping gas. But CO2 is also a trace gas. And, we cannot show statistically that an increase in CO2 concentration in the levels we have seen or even doubling that has any direct and tangible effect on global climate. We cannot show that statistically because we can find numerous periods where CO2 concentration rose but temperatures plummet and where temperatures are higher but CO2 levels are lower. 95% of the green house effect of our atmosphere is due to water vapor, CO2 makes up a fraction of the remaining 5%. CO2 itself is 0.00032~0.00039 of the atmosphere. To use a bad analogy... its like trying to argue that runoff from a garden hose can raise the levels of a river and potentially cause the levies to break. Yes, every drop of water from the hose goes into the river, yes it increases the volume of water in it, but it is all a matter of magnitude and scale. Here are a few things any global warming believer should ponder... The Planet has been warmer at many points in time when CO2 levels are lower The Planet has been shown to cool when CO2 levels rise -- the 1950s thru 70s is an example, 2007 thru present is another example. Ice core analysis have shown that historically, the planet warms first, CO2 levels rise afterwards not the other way around. There have been no hot spots in the upper atmosphere indicating an accelerated green house effect CO2 is a trace gas, its contribution to the total heat trapping ability of our atmosphere is a fraction of a fraction of 5% Androgynous (man made) contributions to CO2 output is a minority fraction of total CO2 generation of the planet We are not currently seeing an increase in global temperatures, we are in fact seeing a decrease year after year since 2007 We may not have all the answers to why the climate is what is or is changing in a manner that it is. But this does not mean that we should make drastic social and economic changes based on a completely bogus hypothesis that is as full of holes as a sift. Instead, we should have an honest discussion about the climate, make plans for what we can do to cope with the effects of observed changes and pursue an energy policy whose goal is a "cheap and plentiful energy" supply, not necessarily one with a reduced carbon foot print, is renewable or is emissions free. The most affordable source today continues to the fossil fuels in their solid, liquid and gaseous forms. We should exploit it to the fullest. This doesn't mean that we shouldn't be looking at other sources -- after all fossil fuel is a finite resource which will become progressively scarcer and more expensive. The next practical source of energy which can provide enough power to satisfy current and future needs is nuclear, not wind or solar, so we should put a much greater emphasis on that and the electrical grid needed for its distribution. We also should advance battery technology so nuclear generated power can be portable -- a requisite for automotive applications. Carbon Emissions and all the "feel good" factors of carbon free energy sources should not be a consideration at all.

Three things... (1) The problem with 2.0 liter engines that make 295 lb-ft at ~2500 rpm is that it doesn't make 295 rpm except when it is on boost -- on full boost. The typical condition at freeway cruise is off boost simply because of the low output require and low accelerative loads. If you rev a turbocharged engine in neutral in the parking lot, it NEVER gets on boost and is always in vaccuum for the same reason. In otherwords, the small turbocharged engine has to be geared such that it still has enough torque off boost to maintain cruising speed. Hence, a 3.6 liter V6 with 275 lb-ft may be geared to make 1800 rpm @ 60 mph, whereas a 2.0T with 275 lb-ft may not. (2) The answer as to whether an entire industry can be wrong is YES. It can. Especially when it comes to popular quasi-axioms like this. (3) I do not expect the Carbon Footprint reduction nonsense to persist over the long run. The non-science of "global warming" is quickly unraveling. The statistics and science behind it are completely bankrupt. The fact is that there is no abnormality with the climate we experience today or in the past 100-years. It is statistically in the middle of historical fluctuations. There is also no evidence that carbon dioxide concentration in the air, especially androgynous CO2, has had ANY tangible effect on global temperatures. We know this because global temperatures have been observed to fall in the 50s, 60s and 70s despite a higher than pre-industrial and constantly increasing CO2 levels. We also know that the medieval era was warmer than today and numerous periods in the earth's history is warmer than today. If you look at ice cores samples going back a million years, you'll notice that the planet did not get warmer following CO2 spikes. In fact, CO2 spikes occur 500~1000 years AFTER temperature has already risen. And, to put a nail into the coffin, the planet has been cooling not warming since 2007 and various IPCC "scientists" have been caught falsifying data to hide patterns they don't like. The only reason this whole charade is still continuing is that it is difficult for politicians and people who support the cause -- unknowing of the actual validity of its science or the lack thereof -- to back track and say they were wrong. To say that they have been pursuing economically ruinous, utterly useless and unnecessary policy. It's potentially a career ending thing to say! But, truth has a certain ring to it and you can't keep it from getting out forever.

The entire forecast of shrinking displacements centers upon the notion that smaller displacement engines are more economical on on fuel. The problem with this line of reasoning is that it is deeply flawed. The most economical engine is not the one with the lowest displacement or even power. It is the one with has the least amount of parasitic losses especially when cruising gently on the freeway. Displacement only contributes to a fraction of this loss, namely the pumping losses associated with moving the amount of air it displaces at a given rpm. However, a smaller displacement engine also makes less torque and will require higher rpms to make the requisite amount required to maintain the said cruising speed. For instance, a 2.0 liter engine turning at 2000 rpm pumps roughly the same amount of air as a 1.4 liter at 3000 rpm. So, the ability of larger displacement engines to run taller gearing partly cancels the benefits of reduced displacement. Hence, reducing the final drive ratio (axle ratio) from 3.23 to 2.86 has the same effect reducing a V8's displacement from say 6.2 liter to 5.5 liters. So, far we have only accounted for effective aspiration rates. However, parasitic losses is not just that. In fact, it is not even mostly that. Parasitic losses is also frictional losses, accessory drag, etc. Parasitic drag from a quad cam 32-valve engine is higher than an equivalent single cam 16 valve engine. accessory drag doesn't change when you reduce displacement or cylinder count. In fact, when cruising on the freeway how well the engine can breathe doesn't even really matter. The engine is being intentionally choked by the throttle body to a specific airflow needed to burn a given amount of fuel that will make the requisite power to keep the car at a given speed. If this isn't done the car will be ssuffering from unintended acceleration. The end result is that reducing engine size can sometimes lead to increased fuel consumption. The Cruze is an example -- going to 1.4 liters and adding a turbo not only did not help fuel economy, it put it 1~2 mpg behind the 2.0 liter competition. The 3.0 liter V6 is either no more economical or 1 mpg worse than the 3.6 in the SRX and CTS applications.

I don't think Diesels are a high priority for GM North America. Unlike Europe, Diesel is more expensive than gasoline, available in a minority of gas stations and view negatively in terms of perceived refinement. Do Americans care about fuel economy? Yes, a little. Is it the #1 concern or the a big enough concern to make the pay extra dollars for a diesel engine and put up with the inconvenience of having to look for specific gas stations to refuel at? Not really. That is why, while VW, BMW, Audi and M-B diesels have found their niches they overwhelming majority -- over 95% of cars sold in the USA are gasoline powered.

GM's reputation in Europe has been that of a purveyor of low quality, low tech cars, that do not perform, do not handle and aren't fuel efficient. Much of it is well deserved given what they churn out in the 80s, 90s and the earlier part of this millennium. Going to a DOHC valvetrain -- with all its disadvantages and advantageous -- will not fix that. In fact, it'll only make matters worse because at least the small block is uniquely American whereas a so-so DOHC V8 is in the mix with everything else and they won't even have a niche to sell into. Going to unique platforms for Cadillac will not fix that either. Fixing GM's reputation is going to take a couple of generation of good if not great products. That, unfortunately, is going to be at the very minimum a decade long exercise. Chasing a meaningless alphabet soup rather than true technical merit is not a particularly good way of going about it.

Well, I am to trying to say that Caddys are dramatically more fuel efficient, but that their uber cars are either in the same bracket or slightly better than competing vehicles in the same power & weight class. Comparing a 4300 lbs CTS-V with its 556 hp engine with a 3900 lbs C63 with 451 hp is stretching the the term "in the same power & weight class". And, this is with the current Small Blocks with no variable timing, not cylinder de-activation and no direct injection -- all features we can expect with the next iteration. Hence, it is reasonable to expect the Pushrod design to be fully competitive with DOHC designs both in performance and in fuel economy. That it is also more compact, lighter and cheaper than a similarly constructed DOHC powerplant shouldn't be viewed as demerits.

Right, and a Cadillac -- even today -- is not 90% a Chevy. The body styles are completely different, the interiors are remarkably better, you get things like magnetorogical shocks which you don't get in a Chevy, plus you get way more amentities and superior materials. I just don't think that Cadillac necessarily have to have its own line of engines or platform to be competitive. It is more important that those engines and platforms -- whatever they may be shared with -- are very good ones. BTW, Lexus, had been outselling BMW and Mercedes in the USA for over a decade right up to 2010. If not for the accelerator pedal witch hunt and the Earthquake, it probably will this year as well. And, the "re-badged Camry" (actually its built on the long wheelbase Avalon platform), the ES350 is its best selling car with 16,596 sold -- more than the LS (4,201), IS(13,015), HS(1,357) or GS(2,080) by a significant margin. I think Cadillac or Buick will be very happy to equal Lexus. It is, after all, the #1 luxury brand in the USA. BTW, I think the Gen V Pushrod engines will compete just fine in naturally aspirated and forcefed forms with the M157 Bi-turbo engine from M-B -- in performance, in fuel economy, in size, in mass and in cost. Just from the anticipated 1 point increase in compression ratio (due to Direct Injection) alone, we can deduce an output increase to about 470 hp NA, 600 with the LSA's level of boost. It is also reasonable to expect around a 1 MPG improvement in fuel ecconomy -- from about 16/24 in an NA 3900 lbs car to about 17/25 and at least equalling the 15/23 MPG of the CTS-V in forced induced form. Both of which are better than the C63's 12/19 MPG or the new 5.5 Bi-Turbo's 15/21 MPG. This is not even counting the effects of added Variable Timing and Cylinder De-activation -- also expected features on the Gen V small block.

Just the numbers to chew on...

Well, GM doesn't exactly put her "sports car" Pushrod V8s in Trucks or vice versa. Is it the same architecture? Yes. But the same engines? No. The truck powerplants are typically marketed under the Vortec brand and they typically have a completely different intake assembly. In part this is because the truck engines do not have to observe relatively short hood heights of the Corvettes, Camaros or CTS-Vs. Hence, the truck engines can have pretty tall intake and air box assemblies. The Vortecs also tend to use cam grinds that biases torque output somewhat lower in the rev range and maximize resonance charging and brake specific fuel consumption at the typical "towing" speeds of 2500~3500 rpm. The current Gen IV Vortec 6200 is the L9H engine which makes 403hp @ 5700 rpm & 417 lb-ft @ 4300 rpm The LS3 6.2 liter engine in the Camaro SS and "regular" Corvette is makes 436 hp @ 5900 rpm with 428 lb-ft @ 4600 rpm. The LS7 7.0 liter engine in the Corvette Z06 makes 505hp @ 6300 rpm with 470 lb-ft @ 4800 rpm The LSA Supercharged 6.2 liter in the CTS-V and Camaro ZL1 makes 556 hp @ 6100 rpm with 551 lb-ft @ 3800 rpm The LS9 Supercharged 6.2 liter in the Corvette ZR1 makes 638 hp @ 6500 rpm and 604 lb-ft @ 3800 rpm To say that they are the same engine is like saying that the Toyota Tundra's 5.7 liter DOHC V8 (3UR-FSE) and the Lexus LS's 5.0 V8 (2UR-FSE) or IS-F's 5.0 DOHC V8 (2UR-GSE) is the same engine... they are, after all, the same Toyota UR-series V8 architecture and shares a similar block casting (albiet with different bore and stroke dimensions).

Actually, I don't think the engine is "unsmooth". It is that the C63 was raw and loud. That, I believe, is mostly the exhaust and most definitely intentional rather than a necesssary measure aimmed at extracting the last few ponies from the powerplant -- the C63 installation "only" made 451hp whereas the same engine in the E63 churns out 518hp. The engine itself is actually a little on the soft side below 3000 rpm. It doesn't choke or stutter, but it's a little lethargic. I am pretty sure its a case of hot, lumpy cams tempered by VVT such that its no longer lumpy but the engine isn't exactly breathing right either. It starts to wake up at around 4000 rpm and really charges between the mid-4000s and the redline of 6800 rpm. This is a motor you can really "feel" when it gets on cam. It also gets loud when put under load; which is either a good thing or a bad thing depending on whether you are the sort who likes an "aggressive" sounding exhaust note. The shifts are very sharp and fast for an automatic when prodded. When driven gently its smooth from 5 mph and up. From a standstill, if you dab the thottle intentionally then back off you can feel the wet clutch "trying" to figure out what to do, but this is largely a non-issue if the throttle input is consistent (gentle or otherwise).

Actually, it has less grit than the AMG 6.3 When the car first came out, they invited all the C55 and C32 owners to a test drive hoping to earn some trade-in conversions. I was among those invited... it was, well, the most raucous V8 I have ever driven. Raw, loud, gritty. I would almost swear that the car has straight pipes to the back without mufflers if not for the fact that it actually does. Next time... when you see a C63 drive by, roll down the windows. IF the guy floors it or even gives it a modest prod, you'll think its trackside at Daytona.

The Cruze is easily GM's finest small car to date. But, I disagree with the above statement... MPG numbers -- after going out of the way to reduce displacement to 1364cc and adding a turbocharger and aftercooler, it hit the market with 36 MPG. This was later bumped to 39 mpg with a revised axle ratio in the 2nd model year. But, even this new rating is 1 mpg behind a Hyundai or a Ford Focus with 2.0 engine. This is a little disappointing. It also goes to show that low displacement does not directly equal fuel economy. Transmission -- The transmission's logic is not particularly smart or decisive. Revs are also on the high side on the freeway -- at least in the lower geared 2011 model. Not sure about the taller geared 2012s. Refinement -- The engine is pretty smooth and refined. It is quieter than the direct injected Ford or Hyundai, partly because it is not direct injected and didn't have to deal with the However, it didn't feel decidedly more refined than the Civic's R18A. The cabin however is the best insulated of the class. Heck, I think its quieter in the Cruze than the 2008 Acura TL.

Actually, it is special. The problem is that that sound is not associated with elite automobiles because American Muscle hasn't "performed" for a long while. But it will be if a new generation of cars with world beating performance sounds like that and people take notice. In any case, a Small Block V8 doesn't have to sound one way or another... that's mostly the exhaust. In terms of loud and raw, the Camaro SS or CTS-V are actually less so than a C63 AMG... Have you heard that thing? its as if it has no mufflers or cross over pipe.

Honestly, I don't think anyone is going to buy a Cadillac-V or some future flagship because of its Pushrod engine or inspite of it. I don't think the valvetrain configuration is relevant. What is relevant is whether you can deliver the performance, mileage and refinement. In this regard, the Pushrod setup trumps the DOHC setup in performance and mileage. However, it is also inferior in terms of refinement -- not because pushrods make more noise, but because a larger displacement is needed for a given output which leads to higher vibration levels from the reciprocating assembly. This, however, needs to be viewed as being as acceptable or as unacceptable as engines like the Mercedes-AMG M156 6.3 liter V8 which is of a similar displacement. The argument that putting DOHC heads on an engine will somehow cause customers to flock to Cadillac or not reject it is dubious. The Northstar did not have that effect and the CTS-V hasn't seen people turn away because of the engine's valvetrain design. DOHC is neither unique (a Camry has had it twenty years ago) nor a symbol of technological prowess, in fact most engines these days don't even inscribe DOHC-32v on the dress cover. It's no longer a differentiating factor when 90% of engines are DOHC. Today, they inscribe things like Direct Injection, GDI, DI-VCT, etc.

Well, I think the "assumption" that Pushrods are a tough sell is overblown. The fact is that it is superior technology and all you have to do is say it. And it's not really contrived to say it. The marketing slogan for a 6.2 liter DI-VVT AFM Pushrod-16v V8 making 470 hp and delivering 25 mpg in an ATS can simply be this... "Cadillac 6.2 V8" ... "470 hp" ... "17/25 mpg" ... "The world's most smallest, lightest, most advanced and most fuel economical 470 hp production engine" And, all of a sudden, you have pseudo gear heads all over the world rethinking their understanding of engines.

More important that trying to figure out what people want -- or at least what you think people want -- more important than focus groups, studies and all that is the need to realize one thing... The USA is a high cost country, we cannot sell faceless products and compete on price or value. The Koreans and the Chinese will win every time. A US company has to be the purveyor of unique and differentiated products, within or without the established mainstream. Companies that realize this do not always succeed, but companies that do not will always fail, if not today, tomorrow.

I actually like the CTS Coupe... and I actually think it looks better than a jaguar XK or Maserati GT. Heck I think it looks better than a Lamborgini Aventador -- which is REALLY tacky -- or A Ferrari 458 Italia. The CTS Coupe has a more unique look than any of these in its proudly inorganic form and its very clean cut styling. I never by new cars -- I cannot stomach or justifythe depreciation in the first 3~4 years -- but I'll probably get the CTS-V Coupe when a 3~5 year old copy becomes available, in the right condition, at the right price. The only question is whether I stick it out in the 2005 C55 until then, or I get a 2008 C63 somewhere in between. The problem is that the C63 isn't particularly pretty and if I get one next year, I probably will be stuck with it until at least 2016. But back on topic... GM does not have the spare cash, time or resources to do a low volume Sports Car on a unique platform just for Cadillac. If Caddy wants a sports car, it'll have to be either an Alpha derivative or a C7 derivative.

30~40 mpg Hybrid I really don't think that ought to be a priority. Car buys as a whole, especially luxury car buyers, is not as green as some politicians and Global Warming coolaid drinkers will like us to believe. GM wanted a halo car and they have the Volt. That is enough for now. The meat of the luxury market is not hybrids, its the 6-cylinder sedans. Money is better spent getting these a couple of MPG better mileage than on a Halo Hybrid. In this regard, I do not disagree with the cancellation of the Cadillac Converj. The market and the volume simply isn't there. DOHC V8 Put simply, the DOHC arrangement is best suited to 4 and 6 cylinder engines trying to meet displacement tax thresholds or engines trying to meet displacement limits in racing due to class rules. A DOHC V8 is inferior to the pushrod alternatives for the purpose of delivering performance and fuel economy. This is because -- for a given power & torque output target -- a pushrod engine is externally smaller, lighter and has lower internal friction, despite requiring a larger displacement. As a side benefit, the Pushrod engine is also cheaper to manufacture. This is not to say that technology should be shunned. The Gen V pushrod engine deserves and will receive state of the art features like direct injection, variable valve timing and cylinder deactivation. 8-speeds Its on the way... it was delayed by 2~3 years as the program was put on ice during the Bankruptcy. Flagship The XTS (ETS) is not the flagship. It is the Lexus ES fighter. Some flagship should be built, but it probably will take a back seat to the ATS and CTS refresh -- and that is probably the right priority. My advocacy is for a RWD flagship based on a stretched Zeta II or Sigma with an optional V12 engine developed cheaply by essentially mating two 3.6 V6 into a 7.2 V12 mill. Sports Car or Convertible The ATS will have a Convertible and a Coupe. The CTS already has what is perhaps the sharpest looking 2-door on the planet. Should Cadillac get a XLR redux? I think so. Basing it on the C7 platform, but powering it with a V12 instead of the Pushrod V8 is a good differentiator.

The Family Zero -- before the 1.4T --- has always been iron block engines. When they did the 1.4T they were looking for the most expedient way to field a 1.4 DOHC turbo four. It was basically the 1.4 Family Zero with a turbocharger. No DI, no Aluminum block. The only concession was they they went to a grey iron alloy which is a little lighter. There reason you'll want to keep the 1.4T is so you can minimize capital and development costs. A 1.4T with DI added is just that. A 1.4T with an aluminum block will be a new engine.

Styling -- I think they are on track Interior Quality -- A little demerit here and there, but they are 90% of the way there Differentiated Features -- Electrochromic windows, magnetorological shocks, something special. Performance -- between a 2.0T & 3.6 DOHC V6, plus a small block powered V they are set as along as they keep weight in check Value -- Don't price yourself out of the market; even Lexus started out selling the LS400 at a $20K discount over the Germans

The methods, practical or not, are reducing weight, using a taller final drive ratio, improving aerodynamics, going to SOHC or fewer cylinders, etc. For Highway Economy, using a final drive equivalent to the 8-speeds top ratio will have the same effect. Improving aerodynamics - such as using a full underbody tray -- will also help. Having less speeds nay cost you acceleration performance. Getting better city numbers entails (mostly) reducing weight, followed by reducing parasitic losses (friction, pumping, etc.) Case an point: The 2011 Camaro (V6 LS model) gets 30 mpg Highway... same 3.6 DI V6 engine, same 6L50 transmission. The difference is the 2.92 axle ratio.

I think that 6-speeds is enough actually. Whats more important is the Ratio Spread. Currently the 6-speeds with two planetaries -- eg. GM's Hydramatic 6L50 or 6T70 is about 6:1, whereas 8-speeds are typically 7:1 ~ 7.5:1. If you can make a 6-speed transmission with slightly wider spaced gears, it'll have the same effect on fuel economy as a typical 8-speed. On the performance front it is more debatable. If you are trying to game the system and get the best 0~60 or 0~62 mph numbers you'll want to hit 62mph either at the end of 2nd or at the end of 3rd. With a 6-speed you'll probably go for 2nd, with a 8-speed you'll go for 3rd. With three speeds to 62, you'll have more torque in 1st and -- assuming you have enough traction -- better acceleration off the line. But, that additional shift will also cost you on the order of ~0.2 secs. In the end it'll depend on the engine. What's more interesting and worthy of thought is this... Many 8-speed transmissions either SKIP GEARS or START IN 2ND GEAR in some operating modes (usually named Economy or Comfort of something along those lines). Heck, forget 8-speeds, even the Mercedes 5 speeds start in 2nd gear in COMFORT mode when paired with the 5.0 or 5.5 V8s (I know, my C55 does that). Why do they do that? Is it because they already have too many speeds for some driving conditions?

Well, before we get carried away in a "Speed War", it is important to recognize what transmissions are supposed to do and whether increasing the number of speed steps beyond a certain point is actually useful. If you distill it to the very basics, having more than two speeds in a transmission only serves two purposes. The first is to provide a Ratio Spread. That is the Ratio between top gear and the bottom gear ratios. Ideally, the bottom gear multiply the engine's output torque as much as the vehicle has traction to handle, hence maximizing acceleration from a standstill. The Top Gear should be as tall as possible to reduce engine RPMs at cruise to a minimum that will still to maintain cruising speeds. The difference between the two is called the Ratio Spread. A Transmission with a high ratio spread will be able to have strong 1st gear Acceleration and top gear fuel economy. This brings us to the second purpose of a multi-speed transmission. Given a wide ratio spread, additional speeds are needed such that the engine can be kept in the meat of its power band getting from the lowest to the tallest gear. If you only have 2-speeds, that 7000 rpm shift from 1st to 2nd may take you down to 1200 rpm which is unaccceptable. Multiple speeds let keep the engine humming in its sweet spot. For most engine, you get maximum performance if you keep the rpms between its torque and power peaks. So... why isn't more speeds better? Because there is a limit beyond which a wider ratio spread is no longer useful or desirable. There is also a limit beyond which additional speeds do nothing but introduce unnecessarily frequent shifting and actually slow down the car's acceleration times! And, we are closer to those limits than some people may think. This is especially true of vehicles with powerful engines. Let me give you an example. The Camaro SS has a 6-speed transmission with a 6.05:1 ratio spread. It already melts rubber in 1st gear to the extent that the fastest launch is not one where the pedal is put to the floor but one where the driver skillfully manages the wheel spin. At the other end of the Ratio Spread, the engine turns over a barely 1400 rpm at 60mph in 6th gear. A 1st to 2nd shift at the 6600 rpm Redline takes the engine from 6600 rpm down to 4516 rpm (within 100 rpm of the engine's 4600 torque peak). Will this car benefit from a 8-speed transmission? Well, lets see... we can use an 8-speeder to create a smokier burnout -- which probably won't be fasster. We can close up the RPM drop between shifts, but that probably won't be faster. We can reduce the top gear RPM at 60mph below 1400 rpm... but not by much before the engine bogs. So what does an 8-speed with closer ratios or 7.5:1 spread or both get you? Probably not very much. On the other hand a lower torque engine or a peakier engine might see some benefit, either to improve acceleration or reduce cruise consumption a little bit. But even then, at some point it becomes counter productive... turning the wheels for 15 mph at 7000 rpm will just melt tires and make a lot of noise. The car won't be able to maintain speed much less accelerate if the top gear is such that the engine turns at 600 rpm at 60 mph. Having to shift 4 times between 0-60 will just slow down the car given that during a shift, power is either not being delivered or not fully being delivered to the wheels for a fraction of a second -- power is instead used to heat up the transmission oil. 2-spds to 3-spds made the car drivable on the street and on the freeway. 3-spds to 4-speeds was a great triumph. 4 to 5 saw signigicant improvements in drivability and mileage. 5 to 6 a smaller difference. 6 to 7... a really marginal gain. 7 to 8 is probably academic. 8 to 9 is mainly a waste of time. 9 to 12, is probably a liability -- both to performance drivability and fuel economy.