We have all heard advice and rules about car care and getting better gas mileage from our family, peers, and auto experts. But is any of it true? Like with most advice, yes and no. Things change over time, and that goes for vehicles too. Most modern cars operate differently today than they did 30 or 40 years ago. Combustion engines now use electronic fuel injectors instead of carburetors. Hybrids and EV’s have changed the fuel economy playing-field even more drastically. So, how do you know if it is helpful advice or just an old wife’s tale? Let’s go over some common fuel economy myths dealing with aftermarket additives, premium fuel, and engine air filters.
Top 8 Common Fuel Economy Myths
1. Size Matters
Small economy cars get better gas mileage than big vehicles, right? Not necessarily. In truth, the size of the automobile does not have as much to do with fuel economy as one might think. Several mid and full-sized vehicles come equipped with direct fuel injection, advanced transmissions, and aerodynamic body designs that deliver excellent fuel economy. Electric vehicles and hybrids are also very fuel-efficient and available in numerous styles and sizes.
2. Premium Fuel Is Better
Higher octane fuel does not automatically improve your miles per gallon. Read your owner’s manual to find the octane recommended for your vehicle. Using a higher octane fuel may be suggested under certain conditions (like towing a heavy load). However, purchasing premium-grade fuel all the time may harm your engine with extended use. In addition, it’s more expensive than lower-grade fuels, so it ends up costing more money for no measurable return.
2a. Aftermarket Additives Improve MPG
According to the Federal Trade Commission, aftermarket additives and devices that claim to improve fuel economy and reduce emissions are primarily shams. Most claims have proven to be completely false when independently tested. They can also harm your engine’s internal components and increase harmful emissions.
3. Manual Transmissions Are More Economical
Modern automatic transmissions are substantially more efficient than they used to be. Due to electronic controls and extra gears, they often provide the same or better fuel economy as their manual transmission counterparts.
4. Dirty Air Filter Wastes Fuel
Today’s fuel-injected engines have built-in computers that automatically adjust the fuel/air ratio to be fuel-efficient. While a dirty engine air filter does not directly affect fuel efficiency in most vehicles, it may lower your engine’s overall performance. It’s still a good idea to replace a dirty air filter. Just don’t expect it to increase fuel efficiency.
4a. Carburetor Caveat
In older autos with carburetors, there is no computer system to automatically adjust the air/fuel ratio. Therefore, they will actually be more fuel-efficient with a clean air filter.
5. Engines Need To Warm Up
If you live in a cold climate, you probably believe that you need to warm up your car for at least 5 minutes before it is safe to drive. In reality, this is a complete falsehood. You can safely operate a modern vehicle immediately after start-up. In fact, anything longer than 30 seconds can be considered a waste of fuel.
5a. Towing Heavy Loads
With every rule, there are exceptions. If you are towing a heavy load, let the engine reach its average operating temperature when driving in freezing temperatures.
5b. Carburetor Caveat
Older autos with carburetors do need to warm up a bit longer to operate efficiently. A cold engine cannot properly mix the fuel and air necessary for combustion. Consequently, it may stall if driven before the engine has warmed up sufficiently.
6. Older Cars Use More Fuel
The EPA routinely tests vehicles to gauge fuel efficiency over their life span accurately. New cars typically continue to improve their fuel economy over the first several years of use. Studies show that even 10 to 15-year-old vehicles show only a minor decline in MPG when routinely serviced.
7. Restarting The Engine Uses More Fuel Than Idling
Idling can use up to a half-gallon of fuel per hour, costing more than 2 cents per minute, depending on current fuel prices. If you are sitting in a parking lot for more than a couple of minutes, it is more cost-effective to turn off your engine. Manually turning off your engine while stopped in traffic is unsafe. However, several hybrid vehicles come equipped with an automatic stop-start system that helps increase fuel economy.
8. EPA Fuel Economy Numbers Are Guaranteed
Fuel economy numbers provide an unbiased method of comparing fuel efficiency in different vehicles. The numbers are compiled from testing that mimics real-life driving situations. The test’s downside is that people do not all drive the same way or in the same places. Your specific MPG will be different from my MPG, even if we drive the exact vehicle in the same general location. Therefore, the numbers are only estimates, rather than guaranteed.
Routine Maintenance Is No Myth
Routine maintenance is one of the easiest ways to maintain fuel efficiency with your Japanese Import. Most modern vehicles can go far longer between service intervals than older cars. Be sure to check your owner’s manual for your factory-recommended maintenance schedule.