i think the one that is in the interior of the car is a electric fuel pressure gauge, that is why im guessing that you said the price for it is $250. there is also a fuel pressure gauge that must people use that goes under the hood. it is connected to the fuel filter or fuel regulator. im not sure but i think i seen people have it connected to a fuel line somewhere. most of the time you dont really need to know what your fuel pressure is. when adjusting the fuel regulator, its easier to see the fuel pressure gauge if its under hood, so you know what psi your fuel is.