My idea is multiple engine sounds for different cars. for example Then moonhawk has an i6 but people make have a v8 even with an i6. My guess is good computer work you can make multiple engine sounds for different cars. 2 and 4 stroke sounds for the pigeon and t series i6 and v8 for moon hawk and barstow V8, or hemi and a diesel sound for d series. and so on
