Extending Your Vehicle's Driving Range, Without Cost, by Steven B.
Saturday, Aug 17, 2013
A while back, I remember reading a tantalizingly titled but substantively misleading news article about a group of junior high school students who built a “car” that attained a fuel efficiency of 150 mpg. After reading the story, my skepticism was confirmed that a bunch of junior high school students “out-engineered” those who engineer automobiles for a living, or more succinctly for profit. The vehicle they built was little more than a soap box racer with a Briggs and Stratton lawn mower engine; more of a go-cart instead of a practical conveyance.
What I did discover in reading the article was that the efficiency was much more attributable to simple driving techniques rather than technological innovation. I immediately saw the opportunity to save a few dollars. When I practiced and developed these driving techniques, it was no longer a matter of saving a few dollars. Upon extrapolating it out over the course of one year, it was over $300 which is quite substantive to me.
Pulse and Glide Driving (PGD) was the term used in the story and it very effectively captures the essence of the technique. It is not difficult to deduce the practical application from just those four words. I have applied this to my regular driving habits, which living in a major city suburb limits me to about 90 percent city driving conditions. I have proven that it does indeed work in stop and go traffic, although not as effectively as dramatically as it does in highway conditions. There are other factors I have also incorporated to further reduce the impact of fuel expenses on my wallet. I will mention them here as well, but be mindful that the bulk of the improved efficiency is gained by cyclical periods of moderate acceleration and coasting along in neutral.
First, let me tell you about my vehicle. I do not have a good bug out vehicle. I drive a sensible commuter in the form of a 2008 Kia Rondo and my commute to work is less than two miles. In the South Florida summertime with the air conditioning running, it gets about 16 mpg city and 19 mpg highway. Using PGD, I routinely inflate those figures to 20 mpg city and about 25 mpg highway, and that is with the air conditioning still running. These figures represent approximately a 25 percent improvement without installing a penny’s worth of performance improving equipment or sacrificing environmental comfort. You would be totally surprised (or not) how important both those notions are driving around with three females; two of them under the age of eight.
The basic principles of PGD are very simple:
- Accelerate to a good cruising speed and decouple the transmission (means shift into neutral for automatics or push in the clutch for standards). When in neutral, keep your foot completely off the accelerator. An idling engine burns little gas and keeps your hydraulic and electrical systems working to maintain steerage and braking capacity. Use your vehicle’s momentum to keep going down the road for as long as practical before re-engaging the transmission for another stretch of acceleration.
NOTE: You may want to get the engine’s RPM up a bit from idle before re-engaging the transmission to reduce the mechanical stress on the power train as it begins to apply force to the ground again. This takes practice to get the transitions smoothed out and is not completely necessary.
- Use downgrades to your advantage. Let gravity accelerate your vehicle while your engine sips the same amount of fuel as it does sitting at a stop sign. This is especially effective in hilly or mountainous areas. I have averaged 32+ mpg in West Virginia on a road trip; doubling my city mileage and by far my best record!
- Shift into neutral when approaching red lights and stop signs. There is no reason to be burning any more fuel than at idle coming up to a place at which you know you need to stop. Additionally, other drivers (even those following closely behind you) will have little reason to become angry since it’s obvious why your speed is bleeding off.
- Try to keep your cycles fairly even. By this I mean accelerate to your cruising speed, coast until about 10 mph have been bled off and accelerate again to cruising speed. There does come a point of diminishing returns if you coast to a dead stop before reaccelerating.
- Do not use more braking than is needed. Every time you tap the brake pedal is energy burned off your brake pads instead of moving you down the road. Do not be fooled by “engine braking” either. Using an engine to slow your vehicle is not very effective and puts additional mechanical stress on your engine. Brake pads are much cheaper than engines and far easier to replace.
- Do not make your target cruising speed too high as this will reduce your efficiency. Any pilot will tell you that induced drag is not a great thing to have more of when it is you paying the fuel bill. The faster you go, the harder the apparent wind pushes back on your vehicle no matter how aerodynamically it has been constructed.
- Avoid accelerating too quickly as jackrabbit starts do not burn fuel as completely as does a moderate acceleration. If you are in a situation where you do need to move quickly as a matter of safety, then by all means punch it without a second thought. Fuel is far less expensive than life.
There are also a couple extra things you can do to stretch your tank’s range even more.
- Reduce the load on the engine as much as possible. Air conditioning is something that you might not want to do without depending where you live, however the electrical load of headlights are totally unnecessary in clear daylight hours in all but the most unusual driving conditions. Any other high current devices should also be shut off or otherwise disabled when not needed.
- Although ethanol blends are nearly universally distributed as the main gasoline fuel supply, search for pure gasoline retailers. Make trips there a couple times a year with your gas cans and rotate them accordingly. Pure gas contains no ethanol, burns more efficiently and will increase your mileage since an inefficient fuel is not being added. Go to Pure-gas.org and see if a retailer is open for business in your area.
This is all well and good, but there are times when you definitely should not use PGD techniques.
- By constantly varying your velocity on the highway in heavy traffic, you are sure to earn the enmity of all who are driving behind you on cruise control. Exercise good judgment and employ PGD techniques only when conditions allow.
- If you’re on a busy secondary road with traffic close behind you, do not make yourself a nuisance. Just drive normally until you have a quarter mile or so of empty space behind you.
- Do not accelerate to unsafe speeds in order to get the longest glide possible. If you have to ask why, then go find the nearest cast iron frying pan and beat yourself in the forehead because you are an idiot. A speeding ticket will negate half a year’s savings. Additionally, fuel savings are of little consequence to the dead. Keep it sane.
- Do not expect to develop the technique too fast. If you are like me, get used to the idea of steering with your left hand a lot while operating the gearshift with your right. I was surprised how sore my left arm became on long trips. Other aspects of PGD require much practice to develop and you should not expect to be great at doing it right from the start. Be patient with yourself and the results will come as you put more thought into what you are doing.
Another thing to think about is by developing and refining these techniques is that you are not only going to save money now, but you are also extending the driving range of your vehicle. A tankful of gas that used to get me only 250 miles now gets me 300; more if I turn off the air conditioner, headlights and parking lights. In the less austere times that could lie ahead, this may be an important factor. If maximum range is of the most importance to you, use the highest grade premium gasoline you can get. For everyday driving however, use the lowest octane rating that provides acceptable performance without engine knocking or pinging. It’s also cheaper, which is the whole point here. Imagine the extra preps you could have after just one year!
If you are on the road to your retreat for a permanent move, incorporating these techniques could mean the difference between getting there with the fuel you can carry drawn from your own stocks or facing the reality of having to obtain more fuel along the way. It may be prohibitively expensive, dangerous to scavenge or outright unavailable at any price. Bring your jerry cans and have a few 5 Hour Energy drinks readily available-- you never know when you might need them.
JWR Adds: Be advised that coasting in neutral is banned in some jurisdictions, for safety reasons. "Gliding" can be hazardous in areas with traffic congestion. Also be aware that you can burn out your clutch if you don't fully disengage it during your "glides." FWIW, I used to turn my engine's ignition off just before very long downgrades (which is illegal in many jurisdictions.) But of course with modern steering column locks, this is no longer possible with most manual transmission cars and light trucks.
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