what can you put in your car to add horsepower, save gas mileage , and get the most we can out of it
3. Tire Pressure. You can improve your fuel economy by up to 3.3% just by keeping your tires inflated to the proper pressure. It takes more effort to spin flat tires, under-inflated tires can lower gas mileage by 0.3 percent for every 1 psi drop in pressure of all four tires. Check the sticker inside your driver's side door jamb, in the glove box, or in your owners manual for proper tire pressure.