How fast can the HoverQuad travel over terrain?

It varies depending on the planet's atmosphere and gravity and the height it's ridden at. Like all grav-lev vehicles, the max is currently around 200m/s on a planet's surface, which is similar to the bikes. However, the bikes have much sharper acceleration curves so reach maximum speed much quicker than the HoverQuad. All grav-lev vehicles can travel faster in space.