Cal Poly’s Supermileage Vehicle Team knows a thing or two about how to get the most mileage—the team’s futuristic prototype vehicle got 2752.3 mpg at the Shell Eco-Marathon Americas in 2008.
While their car isn’t street-legal and isn’t what most of us probably have in mind (three wheels, under 100 lbs., crazy-safe harness), we can learn about efficiency and performance trade-offs in everyday cars by utilizing their experience and knowledge.
Team manager and mechanical engineering senior Verent Chan gave me some tips about how to get better gas mileage. With gas costing around $3 a gallon, who wouldn’t want to save a few bucks?
So in addition to regular maintenance, here are Verent Chan’s top five ways* to get better gas mileage:
Turn off the AC – We live in SLO, where temperatures never get too blazing. The compressor for the air conditioning in your car takes power from the engine in order to run. However, opening the windows will create more aerodynamic drag. During city driving, speeds are low enough that opening the window is acceptable.
Take off those roof racks – Aerodynamics affect your car’s gas mileage more than you think, especially at higher speeds. By taking off those snowboard, ski and surfboard racks when not in use, the car’s aerodynamic drag can be drastically reduced. This also reduces weight, which can adversely affect your gas mileage.
Obey the speed limit – Drag force is a function of velocity squared. The power required to drive a car with that drag force is a function of velocity cubed! It takes 20% less power to drive a car through the air at 65mph as it does at 70mph. The difference in fuel economy can be drastic.
Minimize the amount of acceleration – More fuel is consumed accelerating from a stop than during cruising. When a light turns red ahead of you, take your foot off the gas and coast up to the light. Try to arrive at the light just as it turns green without having to come to a complete stop. Taking longer distance routes that have little stops will often save more fuel than taking the shortest route but having to stop often. Easing up on the gas pedal and accelerating slower can also help.
Monitor tire pressure – Keeping tires properly inflated is the easiest way to keep your car’s fuel economy high. When tires are not properly inflated, rolling resistance increases. Overinflating tires can increase fuel economy even further, but is very dangerous, decreases the life span of the tires and is never recommended. Buying low rolling resistance tires can also help in saving fuel.
*Chan is quoted directly for all fuel-efficiency tips.
Why not try a couple, or even all of these tips out, and see if they make a difference in your car’s fuel-efficiency? And if you can think of any practices you use regularly, please, share them with the rest of us.