Don't you people think the tanks should go faster than 50-60 km/h? The same problem applies with many, if not all, ground vehicles except the bikes. They go fast enough. The side track of the speed is the gravity "engine". I think it needs a little filing too.
One nice detail to be added. The bikes ride faster (constant velocity) than the Humvees in the woods and the Humvees drive about 15 km/h on the bitumen (on a dock). Also aren't the vehicles oversteering?