Lower revs and stronger construction to withstand the higher compression but I wonder what the uber diesels will last like, the 335d for example, specific output is getting on for 100 bhp/litre.
Design and quality is a big factor, look at the K series, damn good little unit with a cruicial design flaw that sunk it, Honda did something similar, no design flaws and slightly heavier construction and it goes forever.
The gender of the owner has an impact as well
