Rather than having the "exhaust" sound and "engine" sound just be front/back of the car, why not make them come from specific nodes? For example, the "exhaust" sound should come from the active exhaust node (the one emitting smoke), the "intake" sound should come from the node that gives water damage to the intake, and the "engine" sound should come from a random (or specified) engine node. It would make the sound engine more realistic, so I hope this will me implemented if/when specific intake and exhaust sounds are added.
Agree. I've voiced my opinion regarding this in the audio feedback thread. Will even be nicer if we can use more than one sample sets (currently only engine sound set with off and onload) but truly separate sfxblend for engine and exhaust.