you can buy a venom speed meter it works spot on , the hard part is finding a location for the little magnet and sensor pickup , i put one on my jato3.3 and got a max speed of 77kmh , the way it works is you put a ruler on the ground next to the car starting from the rear wheel then move the car forward until the tire has made one complete revolution , then you look on the ruler how long was the distance for that tire to make its revolution , then get the measurment and multiply it with a special number thats on the instructions then get that final number and put it into the meter , after that it gives you accurate speeds of how fast your going .
but thats alot of stuffing around id just buy that hotwheels radar gun and that sounds like a good idea
