No test can accurately predict fuel economy for all drivers and all driving conditions. Driver behavior, driving conditions, vehicle maintenance, fuel characteristics, weather, and other factors can all affect fuel economy significantly as explained here.

EPA estimates are based on laboratory tests conducted by manufacturers according to federal regulations. EPA re-tests about 10% of vehicle models to confirm manufacturer's results. For more detailed information, visit our page on How Vehicles Are Tested.

If your fuel economy is excessively low, your vehicle may need to be serviced or repaired. You may want to contact your dealer or a reputable repair facility to check your vehicle.

That depends on how big a cliff you push it off of! Seriously, it varies quite a bit, depending on speed, wind, and fuel type. We can depend on a solid 18 liters/100 kilometers (13 miles/gallon) over long Interstate highways at 100 k/h (65 m/h). We've calculated as good as 16 l/100km (15 m/g) at highway speeds with a nice tail wind. Biodiesel seems to be slightly less, straight vegetable oil (SVO) seems to be slightly more.

Three different sets of fuel economy values- NHTSA’s CAFE values, EPA’s unadjusted dynamometer values, and EPA’s adjusted on-road values exist. NHTSA’s CAFE values are used to determine manufacturers’ compliance with the applicable average fuel economy standards and to develop its annual report, the Automotive Fuel Economy Program Annual Update.

Your mileage may very, but in the 5 gallons per hour realm, up to 6 gph with some engine/power combinations.

You have to ask??? Seriously, the more "stock" the engine is, the better the mpg. You could get 14-18 mpg out of a low horsepower 390, but with 550 bhp, you'll probably get 8 mpg. If you want the best reliability, stick with a stock engine. Unless you throw a lot of money at an engine, higher horsepower will always result in higher maintenance.

It will. Reduced friction means better fuel efficiency with Tufoil. In spite of the wide variations of engines and drivers, independent tests have shown significant improvement with Tufoil of well over 5%!

Fuel economy is lower when E85 fuel is used because ethanol has lower energy content than gasoline. Since E85 is generally lower in price than regular unleaded, cost per mile may be similar. Use of E85 actually keeps the fuel system clean and acts as a gas line antifreeze. Since the major differences in a flex fuel vehicle are the materials used in the fuel system, 85% ethanol fuel does not harm these engines. E85 can only be used in vehicles designed for its use.

The Duramaximizer activates during increased loads and will therefore be able to maintain a taller gear ratio. For example in 5th instead of forth, or 4th instead of 3rd and so on, which decreases the engine’s RPM. This in turn decreases the amount of fuel that is injected into the engine thereby reducing fuel consumption, which then increases fuel mileage.

It rather depends on how it is used. Best economy is achieved from spark ignition engines by running near to full throttle (not at high vacuum according to some popular beliefs) and at moderate engine speed. Hence use of the highest possible gear will generally deliver best economy. Improving responsiveness and mid-range torque makes this more easily achievable in normal driving so can aid highway cruise economy, however use of full available performance will always use a lot of fuel.

I'll make a few quotations here from the Gilpin book I mention somewhere below. You may be surprised that political economy as a term preceded economics..

There is a relationship between air filter restriction and mileage. The theory behind this is simple, the harder an engine has to work to suck air through the intake tubes and air filter, the more gas gets wasted in the process. Replacing a dirty or clogged air filter is one of many recommendations the U.S. Department of Transportation suggests for improving fuel economy (see http://www.fueleconomy.gov/feg/FEG2007.pdf).

It is worthwhile to note that the Chalet is a prime example of 1970's technology, or rather, lack thereof. While it features electronic ignition and power steering and might have cruise control, you should not expect the luxuries of today's vehicles. This includes fuel economy. Between a big V8 engine, and an aerodynamic coefficient of a brick, you should expect single-digit mileage. Driving style also affects mileage; above, say, 65MPH, you can watch the gas guage drop.

A. Fuel economy with the RICA ECU upgrades will improve in 99% of cases. Expect approximately 10% better fuel economy. Most of our customers have seen an extra 4 - 6 mpg.

In most cases, yes. Due to the scavenging effects of an efficient design of headers, more clean air fuel mixture can be delivered into the cylinder bore resulting in a more powerful power stroke. Quite simply this means that the engine does not have to work as hard to deliver the same power. The biggest cause of excessive fuel consumption in this case would be driving behaviour.

Fuel economy is increased by improving the efficiency of your engine which means, releasing energy that the engine is already producing. Improving the engine's ability to breath contributes to the engine's ability to operate more efficiently. An aFe cold air intake system and a performance exhaust system will provide a good benefits to fuel economy.

Although roots superchargers have significant parasitic load and do dramatically decrease fuel economy, centrifugal superchargers will yield approximately the same fuel economy as normally aspirated engines, under normal throttle conditions. When racing, however, fuel enconomy will decrease given the supercharged engine's ability to consume additional fuel and produce additional horsepower.