BMW and MINI – Seven Simple Ways To Save At The Pump – How To Increase Fuel Economy
If you knew of a gas station that would give you a free gallon of gas with every fill-up, you’d make it a point to buy your gas there, wouldn’t you? That’s essentially what happens when you improve your BMW’s gas mileage by just 8%. For example, the computer on our 2001 325xi says we average 24 mpg (city and highway combined). If we could improve that by 8%, we’d get almost 26 mpg (25.92 to be precise), which means for every 14 gallons we burn we would travel an additional 26.88 miles. That’s like getting a free gallon with every fill up!
“Eight percent,” you think. “That sounds like a lot.” It’s not. In fact, depending on the condition of your BMW, you might be able to improve your mileage by 16% (or more!), which is like getting two extra gallons per fill-up. Here’s what you can do to improve your mpg and save at the pumps.
1. Perform an ignition/engine management tune-up. (See Spring 2005 Fast Times.) Studies have shown that a poorly tuned engine can waste as much as 10 to 20 percent of the gas in your tank, depending on a car’s condition. Items you should check/replace include:
- Spark plugs - We recommend Bosch spark plugs.
- Ignition wires - Used on BMWs without coil-on-plug (direct-fire) ignitions. For a small additional cost you can upgrade to our high-performance ignition wires. They provide a hotter spark for a more complete burn, giving you additional firepower and less carbon build-up (and they have a lifetime warranty!).
- Spark plug connector boots – For BMWs with direct-fire ignitions. Replace them when you replace your spark plugs.
- Cap & rotor – For BMWs without direct-fire ignition.
- Ignition coils - Older BMWs use remote coils; newer BMWs with direct-fire ignition have individual coils on the spark plugs. New coils can renew the spark plugs’ firepower. For even greater fuel economy, use our high-performance ignition coils. They also create more torque at low rpm and give you more horsepower at high rpm (lifetime warranty too). (Summer 2005 Fast Times.)
- Oxygen sensor(s) – According to the Department of Energy (DOE), replacing worn-out oxygen sensors can improve mileage as much as 40 percent. (Fall 2004 Fast Times.)
2. Change your filters. According to the DOE, replacing a clogged air filter can increase your mileage by 10 percent, depending on how dirty the filter is.
Replacing the fuel filter is also a good idea because a partially clogged fuel filter can cause the engine to run lean (not enough fuel), which actually makes it use more fuel in order to produce the same power. And don’t forget your BMW’s charcoal canister!
3. Change your oil. Using clean oil reduces wear caused by friction between moving parts. It also removes harmful substances from the engine. Using synthetic oil like Liqui-Moly Voll-Synthese – recommended by BMW in Germany – is an even better idea. Why? Synthetic oil reduces friction better than traditional mineral oil, increasing efficiency and fuel economy. (Winter 2006 Fast Times.) And not just in the engine! We also recommend you use high quality synthetic lubricants throughout your BMW or MINI, further reducing friction and increasing available power and fuel economy.
- Synthetic differential oil. We highly recommend Liqui-Moly and Redline.
- Synthetic transmission oil. Again, we like Liqui-Moly and Redline.
- Synthetic power steering fluid.
If your BMW is your “daily driver” (i.e. not taken to the track or autocross events), another way to save fuel is to use a lighter weight synthetic engine oil. The lighter the oil’s weight, the less resistance the engine faces. That reduction in resistance translates directly into better gas mileage. We recommend Voll-Synthese 0w-40; it’s thin enough for easier start-up, yet protects at higher temperatures.
4. Liqui-Moly’s Jectron and Ventil Sauber - Use this “dynamic duo” to clean the fuel system and control carbon build-up on valves. We recommend a program that starts with a can of Jectron ($7) in one tank of gas, followed by a can of Ventil Sauber ($5) in the next. (We like to refer to this as our “$12 tune-up.”) We suggest you then alternate the two additives monthly; for example, Jectron in August, Ventil Sauber in September, etc. This regimen does wonders for engine performance. Both additives are available in individual cans or money-saving six-packs.
5. Read your engine fault codes. If your “check engine” light is on and you don’t know why, you could be wasting a lot of gas. Our fault code reader can help you identify what to fix on your BMW. (Spring 2005 Fast Times.) Not only will a proper-running BMW use less gas and perform better, you’ll have an idea of what’s wrong before you take it to a mechanic, (which could save you even more money).
6. Maintain your tires. It’s a simple fact of physics: underinflated tires require more energy to roll, and that means more frequent fill-ups. According to the DOE, you can improve your fuel economy by about 3 percent if you just keep your tires inflated to their proper pressure. The recommended tire pressure for your BMW can usually be found on the jamb of the driver’s door or inside the glove box door. (The psi number on the sidewall of your tires is the maximum pressure of the tire, not the proper inflation level.) Do not rely on the pressure gauges on those “Add-A-Quarter” air pumps. They can be off by 20% or more. Use something accurate, like our precision tire gauges or our easy-to-read digital tire gauge.
7. Modify your driving habits. Nobody likes to hear this, least of all BMW drivers who enjoy spirited driving, but being smart about your driving can have a huge impact on your fuel consumption. Here are a few simple suggestions:
- Minimize stop-and-go driving. In city driving, nearly 50 percent of the energy needed to power your car goes to acceleration. If you can anticipate traffic conditions and don’t tailgate, you may be able to just slow down instead of coming to a complete stop, improving your fuel economy by five to ten percent.
- Avoid unnecessary idling. As a general rule, turn off the engine if you anticipate a wait of more than one minute. No matter how efficient your car is, unnecessary idling wastes fuel, costs you money and pollutes the air.
- Remove excess weight from the vehicle. Avoid carrying unneeded items; an extra 100 pounds in the trunk reduces fuel economy by one to two percent.
- Reduce drag. If you have a removable roof rack or rooftop carrier, install it only when absolutely necessary. Not only does it add extra weight, it increases aerodynamic drag on the vehicle, which contributes to a loss of fuel economy.
The majority of what we’re recommending in this article are basic maintenance procedures you should be doing anyway. If you haven’t done them recently, it might not be a bad idea to do them now. Besides, these procedures will not only save you money at the pump, they’ll improve your BMW’s performance. (Who doesn’t want that?!) Plus… you can do every single one of these procedures yourself, saving you a bundle over what the dealer would charge.