10 ways to save fuel

This post offers eleven tips for improving your gas mileage.

The most important are about style and speed, but every little helps.

Getting better fuel economy is just one way to cut driving emissions.  In time we will also cover driving less, sharing more trips and choosing a lower carbon vehicle, but getting better gas mileage from your current car is a good place to start.

1: Monitor your fuel economy

It may be boring, but it matters in two ways.

Firstly, over multiple tanks of fuel or for consistent trips, like commuting to work, measuring fuel economy helps you to see if making changes to your driving has a considerable effect on your fuel gas mileage.

Secondly, if you have instantaneous estimate of fuel economy on your dash-board you can use it to help you optimize your driving style for fuel gas mileage.  This is particularly useful for improving the way you accelerate and finding the speed at which your car is most economical.

2: Maintain your motor

Looking after your car can not only help improve fuel economy a little, but is important for safety and the longevity of your vehicle.

According to the EPA having your car properly tuned can improve gas mileage by up to 4%, properly inflating tires can help as much as 3% and using the correct oil is good for up to 2%.

Essentially you want to make sure your car is rolling smoothly and combusting fuel efficiently.  Bad wheel alignment, an under-inflated tire, dirty filters or a dodgy spark plug can let your vehicle down but are easy to fix.

3: Lose some weight

Having unnecessary weight in your vehicle wastes fuel, particularly during acceleration.  If there is heavy stuff in your boot you don’t need, ditch it.

Losing 100 pounds (45 kg) will improve economy by around 2%.  In fact the push to make cars lighter is playing a leading role in improving fuel economy in new cars.

4: Don’t be a drag

Once you get to about 30 mph (48 km/h)  a car uses more energy to overcome wind resistance than it does fighting rolling resistance.  So you want your car to be as aerodynamic as possible for highway driving.

Having your sun roof open or windows down can increase drag a little at higher speeds.  Leaving a roof box or bike rack on will have a larger effect, but estimates vary widely on this from a 1% to a 15% reduction in fuel economy.

5: Be a smooth operator

Accelerating quickly on your push bike is a strain on your legs, and it’s no different for your motor.  But accelerating too slowly can also limit fuel economy if it keeps you in lower gears for too long, where fuel economy is poor.

As a rough idea you want to take 15-20 seconds to get to 50 mph (80 km/h).  This would combine a relatively gentle start in the low gears with a more rapid shift through the middle gears before settling at an economic speed (40-50 mph) in top gears.

Once your reach an efficient speed, maintaining a constant pace avoids wasting energy on decelerating and then accelerating again.  Cruise control can help with this, but some people also find pulse and glide techniques effective.

When it comes to braking, less is more.  Braking takes useful kinetic energy and turns it into waste heat.  Anticipating road conditions and coasting in gear to a stop makes the most of your car’s momentum, as long as it is done safely.

The EPA estimate aggressive driving can reduce gas mileage by up to 33% while Edmunds’ testing found similar results.

If done well smooth driving can also be safer, more relaxed and better for your car.

6: Don’t be a revhead

Over revving your car is an easy way to waste fuel.  As a general rule you want to change up a gear before reaching 2,500 revs.  In a diesel car this figure is closer to 2,000 revs.  Although the optimum revs for fuel economy can be even lower in certain cars.

It is often quite surprising just how early you should be changing up to maximize gas mileage.  Your car’s manual sometimes gives guidance for this.

7: Watch your top speed

Gas mileage normally peaks at a speed of 40-55 mph (64-89 km/h) while using your cars top gear.  It can vary significantly between cars based on the gearing, engine, weight and drag, but after 60 mph it generally declines quite significantly.

Recent research by the Oak Ridge National Laboratory comparing the fuel economy of 74 vehicles at speeds of 50, 60, 70 and 80 mph shows each additional 10 mph beyond 50 mph reduces fuel economy by about 14%.

More simply put, from 50 to 60 mph fuel economy drops by 12%, from 50 to 70 mph it drops by 25%, and from 50 to 80 mph it falls by 36%.

If you are a bit of a lead foot on the highway, slowing down will improve your fuel economy considerably.  Obviously you can only go as slow as is safe, but cutting just 10 mph can pay large dividends and will probably make your driving smoother too.

8: Roll with it

Working with gravity, rather than against it, is something hyper-milers advocate on hills.  Letting your car go slightly slower up a hill, then coasting down the other side in gear will maximize economy by trading some kinetic energy for the stored energy of being higher.  This tactic should only be employed when it is safe to do so.

9: Don’t be idle

Modern cars don’t really need much time to warm up, it just wastes fuel.  If you are waiting for someone, or stationary in traffic, for more than 30 seconds you are better turning the engine off, assuming it is safe to do so.

10: Easy on the air con

Although electric gadgets do use energy in your car, it tends to be a negligible load for the motor.  The only thing really worth considering for fuel economy is air conditioning, which at low speeds can reduce fuel economy by more than 10% on a high setting.


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