Car engine sound

Hello,

I am working on my 1st Racing game, and I worked 24 hours to make this sound system for the first car

http://www.deathanddust.com/engine

What do you think about my system ?
I will add ON and OFF engine(accelerate or not)

Sounds really good! Care to share how you approached creating the sound?

I use 5 samples recorded with my car.
Today I will record a Lamborghini

Sounds great! Is that just the pitch being adjusted on the audio sample? It sounds like synthesis.

Nice recordings. The pitch does sound a little linear through the gears, how but a clutch change effect?