Should I Be Happy With My Mpg?

Speed is everything with these cars, as they're not very aerodynamic. I once had a long drive ahead, a CD player full of discs, and no reason to hurry, so as an experiment, I sat back, relaxed, and set the cruise control to 55. Even with 3.73s and a blower, I averaged 30.1 mpg on that trip. If you have the patience, you can do the same. If you try the same experiment and find that you're still getting poor fuel economy, post back here and we can help you start diagnosing the issue.

On a different vehicle, I improved the MPG I was getting by short shifting it at 2000 RPM and keeping at 1900-2000 RPM on the highway. It was a 3.0V6 with a 5 speed manual trans. IIRC I was able to go from the low 20 mpg to about 26, which for this vehicle combination was pretty respectable.

The formula for better MPG is pretty set. Lower mass, lower rolling resistance, less power. The internal combustion engine is pretty fixed at a mid 20% thermodynamic efficiency. It is also fixed at approximately 14:1 air to fuel consumption ratio. Many times to increase power, we try to increase airflow into and out of the engine (intake, air cleaner, exhaust modifications). When we get more air into the engine, it needs more fuel to keep from running lean and burning up or breaking something. Anything you can do to make any of the factors affecting mileage better will give you an increase. Less mass -- empty crap out of the car you don't need. Less rolling resistance -- narrower tires, harder compound of rubber in the tire, increase in air pressure all can help. Then engine will consume however much air it does per revolution and will burn fuel to match. Keeping the RPMs down is the easy way to use less fuel. The higher gear you can use, the farther you will travel per revolution, better for mileage.

Really, the easiest way to better fuel economy is less mass with less power. That's why manufacturers are offering cars like the Fiesta. Small, light, low power. Less mass also has the side benefit of making less power seem like more. An 85hp motorcycle is more fun to ride and faster than an 85hp pickup truck.

Now manufacturers are playing around with trying to vary the amount of air an engine uses per rev. GM is using selective cylinder deactivation. Ford is going with their Ecoboost. A turbo charger can have the effect of increasing power by processing more air through the engine than natural aspiration, but you need more fuel to do it. If the turbo can be cut out when not needed and let the small engine run NA when less power is needed, you can have an increase in fuel mileage but have more power available when needed by bringing the turbo online.

Just some random thoughts.