התנך לחסכון בדלק .

וזה מה שקיבלתי היום בדואר
אומנם האנגלית אבל הכל נכון גם למדינה העברית .
******

Dear Merkado,

In the last several weeks many of you have emailed me about techniques and tips to improve gas mileage. Let's make that this week's topic.

Today's cars and trucks are designed to run with the best mileage, power and emissions possible, and they do a great job of it. So what can you do to save at the pumps in your vehicle? Here are some tips.

Buy cheap. Don't pay for "premium" unless your manual recommends it. Unless you're driving a Corvette or turbo-charged car, the odds that you need premium are slim-to-none. There's no upside to using higher octane fuel than necessary. Some name-brand fuels may have better additive packages than no-name fuels. I don't have any hard evidence one way or another that it would affect mileage or maintenance, but it is worth noting.

Check your tires. Both for safety and economy. Keep a tire gauge in your car and check your tires every time you fill your tank. Use the pressure recommended for your car (look in the door jamb or under the truck lid for the manufacturer's recommendations).

Put your car on a diet. Don't keep extra weight in your vehicle.

Keep in tune. Keep up with the recommended replacement schedule for ignition components such as spark plugs. Keep a clean air filter. Be sure your fuel injectors are clean (an occasional bottle of injector cleaner additive isn't a bad idea). Use AutoTap or another scantool to be sure that you're not having problems with misfire.

Don't use the brakes! Don't take this one too literally, but there is nothing you can do that hurts your mileage more than pushing the brake pedal. Every time you push the accelerator you've made an investment in your car's momentum. Every time you brake you throw that energy away. (This and the next tip are worth 10 times all the rest!)

Watch your top speed. At highway speeds, small increases in speed require much larger increases in power. Slowing down a few mph on the highway will save you dollars. If you own AutoTap, try monitoring the "Percent Load" parameter at a couple different speeds on a flat highway and you'll see what I mean!

What about all the fuel-saving devices that are marketed so aggressively today? Total waste of money on fuel injected cars and trucks. That certainly doesn't prevent them from selling huge quantities of these high profit-margin products. But, don't mistake profitability and celebrity endorsements for science! The fact that we'd all like to believe that they work doesn't change the rules of physics.

So how do they get away with their outrageous claims and "proven" results? One answer is the use of weasel-words. Remember "Up to 10% Savings" includes the number zero!

Another answer can be revealed with AutoTap. Some of these devices add an airflow obstruction in the intake. While I haven't tested any of these devices, I have seen test results on another engine modification that performs a similar function. The results? The intake air becomes turbulent as it passes through the Mass Air Flow (MAF) sensor. When the air flow is turbulent the sensor gets confused. On some vehicles, this causes the engine to run temporarily lean. This could improve mileage (at the expense of emissions, durability or power). However, if you remember our previous emails about oxygen sensors, you'll recall that these sensors will detect the lean condition, then "learn" how to correct it. What does this mean in real life? For a short time, there could be a small improvement (and this would be a good time to make measurements for advertising claims!). But, give it a week or two and the computer will tune the fuel mixture back to where it belongs, and any gains will disappear. Monitoring the long term fuel trim parameters with AutoTap reveals this behavior.

So don't help fuel that snake-oil industry. Use some of the practical tips in this week's email to improve your economy. Will you see huge improvements? Not likely. But small improvements can add up!

Happy Repairs,