Ive always been wondering about these two things...

First off i was wondering about this safety hazard, when the car is moving it is really easy to just press a button like the off button or the park one...if u do press those will the car go to park or if u press the engine will the car turn off? And when i calculate the mpg in the car by myself (miles/gallon) i get a different number than the one displayed on my computer calculator on the car. And yes i do use the exact same mileage for my calculation as displayed on the energy screen. And the one i calculate is higher too, this has happened many-a-time!