OK after reading this forum i decided to put together my own little sound test by using the Audi R8 and Dodge viper as the test cars. What i did was setup the cars on daytona speedway and used my laptop to find the specific cars sound video on youtube
After testing i found out that the Audi R8 is actually done pretty accurately but lacks the deep sound to the real one, same with the dodge viper the only problem i think is that the engines need to be more louder and more pronounced
As for other games yeah I agree engine sounds can get quite over exaggerated *PGR*