There are quite a few blueprints for editing sounds in unreal engine, the ‘Set pitch multiplier’ blueprint might be what you’re looking for. Generally, vehicular sounds are generated when you mix more than one sound at a time while mixing rates on a multiplier based on speed from the player’s orientation and momentum. On a large truck sound I recently worked on (I wish I could show you), I took white noise, a few different motor sounds, and a sandpaper noise in combination. As speed is gained, the pitch heightens in increments and the lower register increases as gear ratios change. These effects are manipulated by volume spaces to judge distance and speeds, there’s also a separate pitch node for when you’re moving away or towards the vehicle to simulate modulation using that volume space. I don’t believe Unreal Engine has a full audio suite yet, but there are methods out there to do many different things. Look at the vehicle demo in unreal engine to see how Epic achieved their version.
There was a post quite some time ago with a multitude of audio bits for use in game design, there are download link everywhere I’m sure you won’t have a problem finding it.
Edit:
I don’t know if this is what you’re looking for, but it might help you:
http://www.fmod.org/dynamic-car-engine-ue4/