it all depends on how big the engine is. if the buggy is 50cc it will reach 20-25mph, all depends on which type of buggy and the quality of the build. if the buggy is 60cc it will reach around...
The nitro gv cage does 110 kmh I tested mine with a speed gun if this helps you
They CAN get up to like 120mph, but those are VERY expensive, usually around 50-70, as long as you dont but like a 20.00 dollar one.
65MPH
About 45mph maybe 50mph for .21 engine