because you need to accelerate and pass people, which requires accessing the upper reaches of the rpm band, more often than you think.
by your logic then, a 1 speed tranny is the schizzle.
any engine can be smooth at 3,000 rpm. if its smooth at 6500 rpm as well, you know the engineering is solid, not only the that, the vibration from the motor is less of an impact on the rest of the car. lastly, smoothness at high rpm only serves to underscore the quality of a product.
you can have your iron block dinosaurs like the 3800. There is a reason it was passed by by others LONG ago.
Let's see here... no, no, no, no, and no.
NO #1: The need for 6,500 rpm smoothness to pass people? Two words: Racing Diesel. If the torque comes on much stronger at a lower RPM, you engineer the gearbox accordingly.
NO #2: Any engine can be smooth at 3,000rpm? Two words: Quad-Four.
NO #3: Smooth at 6,500 RPM has nothing to do with "solid" engineering. It has everything to do with the size of the reciprocating mass. With a properly configured 6-speed automatic mated to both, I'd pit even the LT-1 against a Nissan VQ any day of the week for solidness.
NO #4: Why is 6,500 rpm the cut off for smoothness requirement? Run a Honda 2.4 up to 8,500 rpm and see how smooth it runs then. Running an engine outside of design parameters will get you unpredictable operation. The 3800 was never intended to be run up that high.
NO #5: The 3800 was done in by it's lack of VVT and it's packaging requirements being a 90 degree engine. The 3900 is a lot smoother than the 3800 was simply because of the cylinder bank angle change. Where GM let both engines down was pairing it with the 4-speed automatic. If either of those engines had a 6-speed auto that was able to keep it in it's designed
RPM range, there wouldn't have been so much complaining about it. Don't start an idiotic horsepower per liter argument, it's already been a long day for me.