well I clocked my RC18t at 34mph with the 11.1v. and 25mph with the 7.4v. I was also clocking passing cars with no problems. Its got a 40 foot max range which is more than enough for Rc's and screwing around. the product literature says is acurate to within +/- 1.5 mph depending on range and size of whatever is being speed checked. It seems pretty acurate even if its off a little from true readings it will still be very fun to compare speeds of different RC's and how much top end you are getting from leaner tunes on Nitro engines. For under $30 though its a fun toy and I bet this thing would set of radar detctors too. I'm going to keep it in the car with me and gun a random car I see with a radar detector.. lol!!