How to Effect Fuel Economy
The three most important aspects of affecting your fuel economy are:
- Rolling Resistance
- Efficiency of the Engine
- Additives and Booster
Rolling Resistance
Tire Pressure - a low tire flattens out and causes increased rolling resistance. An increase in rolling resistance makes it harder for the engine to push the vehicle and therefore wastes gas. In addition, the constant bending of the tire sidewall because it is flat causes the tire to wear out prematurely. If the cost of gas doesn’t scare you, try the cost of new tires.
Tire Styles – Those 22 inch rims might look appealing but if the diameter of the tire increases you are increasing the gear ratio. Just like choosing a high gear on your bicycle makes it harder to push at slower speeds. There are also many manufacturers that make fuel efficient tires now. The rubber is a different compound designed specifically to lower the rolling resistance and increase fuel economy.
Junk in the Trunk – the more weight the engine has to push the more gas it takes. It is not very hard to get upwards of 200 pounds in the trunk. That is whole other person. You might be surprised at how much happier your engine is not pushing around junk.
Lubrication – The wrong viscosity of oil can increase resistance in your motor and waste fuel. If your car requires 5W20 and you use 5w30 instead it won’t blow your motor up but the oil is too thick. It will break down faster shortening the life of the oil and be harder to push around the engine causing fuel wasting resistance.
Efficiency of the Engine
Air Filter – An Olympic running athlete will not run very far or fast with a clothes pin on his/her nose. A restricted or dirty air filter will do the same thing to your engine.
Spark Plugs - It takes 10k volts to jump electricity just one inch at 98% humidity. Your ignition system is probably closer to 40k volts. If the plug is worn out the spark is weak and therefore the fuel does not combust correctly.
Intake Deposits - Deposits that form on the inside of the air intake ducts choke them off making it hard for the vehicle to breathe. No breath – no power – wastes gas.
Intake Valves - Intake valve deposits are hard, crusty, coching deposits that change the state of the fuel before it enters the combustion chamber. Droplets do not burn as well a fine clean mist.
Piston Crown Deposits – The space between the top of the piston and the bottom of the head when the piston is all the way up is about as thick as a human hair. The slightest deposit on the piston crown reduces that space, increases pressure and causes pre-ignition or knocking. Modern cars have a knock sensor which retards the timing robbing you of power and forcing you to press harder on the gas pedal for the same performance. Again…robbing you of gasoline.
O2 Sensor - O2 sensors sense oxygen in the exhaust stream telling the computer that the fuel has not fully burnt. The computer responds by increasing the amount of fuel to burn the extra oxygen. If these sensors or faulty or full of deposits then the computer gets the wrong signal and again…wastes gas.
Additives and Boosters
So what can you do about all the efficiency stuff up above?
Three things…
- Make sure your air filter is clean. If you do not know how to check it, drop on by and we will either show you how to check it yourself or do it for you. Free.
- Always buy the best fuel you can. The LOWEST Octane but best fuel. Chevron, Shell, Conoco, these are the best bet.
- Use a proven additive. Hint … if you can buy it on the shelf it is junk. We recommend either BG Products or Greenfoot Global’s eTabs. We carry them both and have proven on hundreds of cars that they work.
Calculating Fuel Economy
This is a topic that is in the media and all around us. Even though gas prices are currently dropping, which is great, we are still a far cry away from where we were just a few short years ago. Anybody remember paying less than $2.00 per gallon? I can remember prices as low as $.50 but that dates me a bit. 
If you do not have a computer on board your vehicle, how do you know what mileage your vehicle is giving you? Do you really know how to calculate your fuel economy? Even better, any idea how to use this calculation to your benefit?
calculate miles per gallon
Well simply put, fuel economy, in this country, is measured in Miles Per Gallon or MPG. So if you have a 10 gallon fuel tank and you drive 300 miles then you divide the 300 miles by the 10 gallons to get 30 MPG. Easy enough. The math gets a little more complicated in the real world but the formula is always the same. Here is what I mean.
If you have that same 10 gallon tank you probably do not empty it and cough your way into the gas station. In reality you probably purchase 8.3 gallons or some odd number like that. Then the odometer reading at your last fill up was … say … 120,000 miles and now it reads 120,287. So that leave 287 miles driven for 8.3 gallons of gas or (lemme get my calculator out) …um … 34.578 MPG.
OK…now…so what?
I mean, you gotta buy gas. The tank is on empty. You gotta get to work. Who cares about the mileage? Right?
Wrong.
There is no better performance meter of how your vehicle is running than MPG.
So much affects it. Like:
- How you drive
- Hiway or intown
- Leadfoot or little old lady
- Towing a trailer?
- Tire condition
- Engine tune
- Spark plugs/wires
- Air filter condition
- Fuel filter condition
- Grade and age of oil
- Intake deposits
- A/C on or off
- Extra weight
- Passengers
- Trunk denizens
There is a lot that can affect your vehicles performance and monitoring fuel economy will tell you when the changes and trends are small and can be dealt with inexpensively. You do not need to be an expert mechanic to tell that the performance is waning. You just have to be able to track a simple little number.
For those of you with Smart Phones it gets even easier. I have an Apple iPhone and I use a program called Road Trip. It does all the calculations for me and then graphs the result. Takes seconds and is even kind of fun. This program even tracks what it is costing me to operate the vehicle per mile/week/tank fill up/ or year. Great for taxes and tracking repairs and maintenance. Check out your Smart Phone’s app store. There might be a solution there for you.
The money you save at the pump can easily pay for the maintenance costs associated with getting the best fuel economy. And a well maintained car rarely needs repair. It is all an awareness thing. You can only control that which you are aware of. Want to fight gremlins out of your pocket book. Pay attention to your fuel economy.
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