Yes and no. The early buses had reduction gears on the ends of the axles -- they could climb a tree, but the engine was about 50 RPM below flying apart, going down the freeway. Not to mention they lacked power at those speeds. The later ones had bigger engines, no reduction gears, and were decent at lower freeway speeds. If you had the time and money, you could build an engine that would push a bus to at least 100 MPH - but they get really scary at that speed.