The 400 only has 1 forward gear, High range, which is like 3rd gear. The 400 has the same top speed as the 500-750 but they have a Low range gear, not the 400. The 400 engine was from the Yamaha 350-400 ATV which weighed 460 lbs. and had 22” tires. Then HiSun copied that engine and installed it in a UTV frame that weighs 1250 lbs and has 25” & 26” tires ! The 400 is perfect for light loads and personal transportation. Remember you are 3rd gear all the time!