I got a gas mileage increase of 15% on my 1992 Camry DLX, 5 speed, no cat, stock resonator and muffler, using 1 1/2 oz acetone per 15 gallon with 100% gas. At 255k miles it would get 33 mpg highway at 55 - 65 mph. The poor thing broke the oil pump drive sprocket, which gave me a good reason...