I just bought this 1990 Olds Cutlass Supreme with a 3.1L v6 engine. The car has 52,000 original miles and is unmolested. When I went for the RI Emissions Test, the car achieved 2.30 gpm, failing by .05 gpm hydrocarbons. The limit is 2.25 gpm. I purchased a 5.25 oz. bottle of Lucas Fuel Treatment and added half of it to about 10 gallons of gas. A week later after driving 180 miles , I went for a retest. The hydrocarbons dropped significantly to 1.93 gpm, passing the test. As they say, THIS STUFF WORKS!!! As of now, I haven't had the car long enough to provide any mileage data.