Using the code "commandtoserver('messagesent',"My current speed is " @getcontrolobjectspeed());" I have compiled the top speeds things can go up to.
Walking: 9.9
Falling without any assistance: 199.3
Jumping on water with density 1000+: 299.0
Jeep: 29.9
Stunt Buggy: 149.9 (I was as shocked as you are....)
Hover Board: 19.9
Flying Wheeled Jeep in the air: 39.9
Horse: 11.9
Magic Carpet in the air: 131.4
Stunt Plane: 89.9
Scooter: 39.7
If you have any other vehicles/speeds for me to test/put up in the list, post below...