Fuel Economy Improvements?

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Aug 5, 2014
San Francisco
I just came across this interesting sidebar in the July 2014 issue of Commercial Carrier Journal where a Yokohama Tire exec breaks down fuel efficiency. For every dollar spent on fuel:
- 60 percent is wasted by engine inefficiency
- 21 percent is wasted by aerodynamic drag
o 50 percent is wasted by the drive position
o 35 percent is wasted by the trailer position
o 15 percent is wasted by steer position
- 13 percent is consumed by overcoming tire rolling resistance (average of all tread types)
- 4 percent is consumed by the load
- 2 percent is consumed by the drivetrain
Based on this info, efficient engines are by far the most important keys to fuel efficiency. What are some of the fuel economy improvements you’ve made to your engine?

"What are some of the fuel economy improvements you’ve made to your engine?"

I think the 60% "waste" is the thermal dynamic limit, unless you can significantly increase the combustion efficiency (without significant NOX emission increase) you won't be able to do much about it.
Sixty percent wasted by engine inefficiency, you say?

I wonder if it would be feasible to get a judge to overturn the second law of thermodynamics... that'd improve that number.
Make one trip to accomplish what needs to be done. Why make two or three trips(my question to my wife) when you can make one and get everything done. Goes over like a *%@# in the punch bowl every time.
Taller 5th gear, reduces RPM's by 1000, 12% fuel economy increase...

Larger, but not wider, tires. Wider tires means more rolling resistance. Speedo is off a little...

Inflate the tires to within 2-5 PSI of max (printed on tire sidewall)

Gentle starts and stops. Coasting when possible, drafting on highway...
That's misleading. The "60% wasted by engine efficiency" is generally true for ALL internal combustion engines. Variations from engine to engine are there, but they are small compared to that 60% inherent limit. Even a Prius has that efficiency factor. Even a Tesla could be given a "30% lost by the power plant" factor in an equivalent way.

Comparing vehicle-to-vehicle, aerodynamics are much more important than engine type. My 392 Challenger has the least efficient (at least for cruising down the highway) engine offered in that vehicle and I get 25 mpg highway. The most efficient engine/drivetrain combination in that vehicle is the 3.6L Pentastar with a TF8 transmission, and it gets around 30 mpg. A difference, but not a HUGE difference because the weight and aerodynamics of the vehicles are identical. People are also always shocked that a Smart car doesn't get drastically better mileage than a Fit or Yaris (in some cases, worse), but its because the short little boxy body is not very aero efficient compared to the Fit or Yaris' more traditional aspect ratio.
Pratically, beyond what the owner manual says, it only remain driving practices. Avoid to try gaining speed up hill, just maintan or even loose a little gradually, then recover at level or downhill.

Or, even better,

Buy a turbocharged one liter/hybrid engine car for city driving and drive it very slowly.

Anyways, fuel economy will be a pain.
Slow down. If you drive 68mph rather than 72, you'll add a couple of miles per gallon (or more) due to reduced aerodynamic drag, as another responder suggested.
Mr. Fusion upgrade; but can't seem to get my flux-capacitor set just right . . . . .

Using bicycle in the meantime; fuel mileage is outstanding!
Don't use the brakes. When you slow down or stop, you have to accelerate again, which uses fuel.

The above statement is just as true as the "60% wasted engine inefficiency".......And almost as useless.

Planning ahead, maintaining a steady speed, and avoiding the brakes will save you more than any other behavior modification. Just sayin'.
Originally Posted By: LoneRanger
Your numbers exceed 100%

I thought that too, but I think the "o" lines are indents, breaking apart the aerodynamic drag.

In cold enough weather (probably not in SF), you can get some minor net gains by using a block heater in the colder temps, and possibly by blocking off some of the radiator.

You can also reduce the rolling resistance percentage by using LRR tires and being diligent on checking the tire pressures.

Like everyone else said, you're not going to make many mods to the engine to increase the inherent efficiency, you're best off trying to use the available power as efficiently as possible.
Originally Posted By: SVTCobra
Strap a jet engine to your truck?

A team of horses.?

Square rigged sail?
Originally Posted By: LoneRanger
Your numbers exceed 100%

The 50/35/15 are a breakdown of the sources of aerodynamic drag. They add up to 100 and all of the other numbers add up to 100.
Originally Posted By: EdwardC
You can also reduce the rolling resistance percentage by using LRR tires and being diligent on checking the tire pressures.

And, try raising your tire pressure up near the high end of the permissible pressure range. The max pressure is molded into the sidewall of the tire.

The downside of this is a somewhat rougher ride and slightly reduced braking ability. With a little experimentation you may be able to find an increased pressure which is a good trade-off. Simple diligence checking tire pressures may be just as good!
The easiest and cheapest route to improved fuel economy is to drive more gently.
Avoid hard acceleration when possible, coast up to red lights to take advantage of the DFSO, learn to time the lights on routes you drive regularly and cruise on the highway at a number of revs just below the rich range of the fuel map.
Gains in fuel economy of 10-20% can be achieved with any vehicle I've had with no more than paying a little attention to what's going on.
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