Four stroke engines Sound incredible! (sounds like a Harley Davidson) They have great gobs of torque! They will climb anything! It will shoot up a 65 degree 100 foot gravel pile without taking a run at it. You can stop half way up, and with a blip of the throttle shoot into the air landing on the top. The 2 stroke trucks are still backing up to get a run at it! They have as much slow speed torque as an electric rock crawler! They work excellent on small tight winding tracks, they are hard to beat! The only thing they don't do is high speed. Top speed is around 30-35 mph.