I finally got around to making a Gyrocopter in A20, and noticed it's listed as 45m/s speed, where as the Motorcycle is listed as 27m/s speed. I do have 2 mods in the Gyrocopter - Fuel Saver and Extra Fuel tank, but these don't mention anything about impacting speed.
But the thing is, The Gyrocopter is VERY noticeably slower than the Motorcycle. I can only really test on the ground as a basis of comparison, so maybe it goes faster in the air(though that would not make sense), but on the ground where as it should have double the speed, it seems to be more like half. In fact, I'm reasonably sure I run faster than it.