These things can't be that accurate. I ran my numbers in mine by using the 1/4 mile speed and weight of the car and this thing is saying I'm putting out 284 hp. I used the door sticker of the gvw minus about 100 lbs from loosing the air conditioning, air pump and part of the interior then added my 160 lbs with a 1/4 speed of 90 mph. Just a guess cause my speedo stops at 85. The sticker says my car weighs 4094 lbs which seems kinda heavy.