The Top 10 Most Highly Tuned NASP Engines - No.9
9. BMW M3 CSL
The E46 M3 CSL is an absolute masterclass in engineering and it's engine is no exception. Piston speed is down slightly from the RS4 at 24.9m/s thanks to a slightly short stroke, but it more than makes up for it with 273lbft from 3246cc, for a specific torque figure of 84lbft/litre.
With 355bhp out of a theoretical maximum of 440bhp, the M3 CSL scores an NA PI of 806!