Your grandpa probably must have misunderstood. There are no "jets" in these cars, he was probably thinking back in the days of carburetors. Even then, they sure as heck didn't cost $800 to clean. At 37,000 miles, you should need no fuel injection system cleaning. However, you should be getting about 10 miles per gallon better than you're doing, unless you're driving it like most teenagers...pedal to the metal all the time. You need to take it to a mechanic and run a diagonosis on it.
