Yes, they usually are, but it can differ from car to car. For example, a Chevy Suburban is faster than a smart car because there are more pistons in the engine, creating more torque and speed,...
If you mean by speed and wether or not it is a production car, then it is the bugatti veyron super sport, it has a 16 cylinder engine with 4 turbo chargers. It produces 1001 bhp and an air brake...
I don't think the HEMI heads were invented/designed until the last 50's/early 60's, when Chrysler/Dodge/Plymouth first made them famous. I will check and see if this is true, but I think it is.
A...