10. Audi RS4

Despite being the first entry on the list, the 2014 Audi RS4 actually tops the list for piston speed, it's sublime 4.2 FSI V8 revving to 8250rpm with the pistons buzzing at a ballistic 25.5m/s!

Although the engine is at the ragged edge in terms of speed, the torque figure does leave some room for improvement. With 317lbft from 4.2 litres, it manages a specific torque figure 76lbft/litre. Entirely respectable, but the lowest on our top 10 list!

With 444bhp out of a theoretical maximum of 554bhp, the Audi RS4 sets the bar with an PI of 802.

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