It is situational with which is faster around a race track.
For the off road vehicles in classes where chassis weight is higher, and there is less downforce in a run what you bring class with little rules the electrics with Lithium Polymer and Brushless motors rule the roost.
For oval racing the lighter weight of the nitro would still hold the advantage. The motor can be tuned for a narrow power band where it really rips.
For "street courses" it would depend on the track lay out.
If you have equal downforce, and one car weighs less, that downforce is worth more.
For racing, there are different classes, so which is faster isn't as relevent as whether you like the noise or don't like the noise.(Or if you want to run in places where people don't like the noise)
