I never used it to measure the HP, so I can't help you there. To get the 0-60 and 1/4 times put the switch into the middle position and then plug it in. You'll see two words flashing alternately: Gfrc and Accl, press the switch (it's also a button) when Accl is displayed. It will be showing current acceleration of your car. Get your car into start position and come to a complete stop. Adjust the Gtech so it shows 0.0 Then press the switch again. The word Go will start flashing. Start accelerating. After you reach 60 mph it will display the time. If that's what you want slow down below 60 mph and then stop. If you want the 1/4 mile time just keep accelerating. It will know when to stop measuring. The numbers displayed will be your 1/4 time and your trap speed. To start another run press the switch.