Lesson 8: Advanced Tips and Techniques
Now that you’ve learned the ecomiling way, you may wish to extend your knowledge and fuel saving options by practicing some advanced techniques. Be warned, though, that these techniques may represent dangerous departures from typical driving techniques and/or may require explicit knowledge of your vehicle’s current fuel economy. At the very least, you may find that you really annoy your fellow motorists.
Safety is vastly more important than fuel economy. Never jeopardize your safety for the sake of fuel economy. It’d be nice if you never had to use a drop of gas again but not if the reason is your untimely death. Please use common sense on the road, observe all posted speed limits, respect all signage and authorities and drive safely.
If you just want to know your vehicle’s current fuel economy and your gauge cluster doesn’t show it, well that’s a snap. Check out the ScanGaugeII. I love mine.
More Economical Cruising Speeds
In Lesson 4, I indicated that the ideal cruising speed is the speed limit, both on and off the freeway. While this is a good general guideline to follow and one that will save you an exceptional amount of fuel, it’s not necessarily true that your vehicle’s fuel economy sweet spot will occur at posted speed limits. In fact, drivers with 4-speed automatic transmissions might wonder how driving at the speed limit both on and off the freeway could possibly be best for fuel economy when their vehicles are in the same gear in both situations.
Well, the short answer is that your fuel economy may actually benefit by driving in excess of or below posted speed limits depending on traffic conditions and your specific car. Your transmission plays a particularly critical role in determining your ideal city and freeway cruising speeds, as does safety. Clearly you should not drive 70km/h in a 50km/h zone, even if that happens to be your vehicle’s most economical cruising speed, but maybe you can get away with 60km/h if that happens to be the general speed of traffic in your area. And maybe that 70km/h would be OK to use on the freeway, where posted speed limits might be 80km/h. Drive a little slower if it saves you money and if you can manage it given traffic conditions.
If your vehicle’s gauges offer up instantaneous and trip fuel economy information, use this information in conjunction with a mind to safety in order to discover your ideal cruising speeds by trial-and-error. If your vehicle does not provide this information, then you will need a ScanGaugeII. Without some way of knowing instantaneous and trip fuel economy information, you’d be wasting your time and probably your gas trying to come up with ideal cruising speeds. At best, it’d be an arduous process and in such a case you’re best off sticking to posted speed limits.
Pulse and Glide
Also in Lesson 4, I indicated to you that the best way to maximize your vehicle’s fuel economy was to maintain a constant cruising speed. And once again, depending on your specific vehicle and driving conditions, this is not necessarily going to be the case. The technique of pulsing and gliding, namely repeatedly accelerating to (or slightly above) posted speed limits and then coasting down below them can under some circumstances help you achieve substantial fuel economy improvements over and above the already very economical coasting techniques of Lesson 4.
Most people consider pulsing and gliding a hybrid-only technique because hybrids shut off the gasoline engine when not in use. This is only true to some extent, though, because modern fuel injected vehicles also shut off their fuel consumption in some situations. Remember deceleration fuel cutoff (DFCO)? Hybrids are particularly suited to pulsing and gliding, and hybrid drivers can reap massive rewards through proper and conscientious application of pulse and glide techniques, but that doesn’t mean pulse and glide is for hybrids only.
If you drive a hybrid, then you can practice pulsing and gliding almost any time the road you’re travelling is reasonably clear and flat. Pulse and glide does not work in undulating, hilly terrain and it may not be safe or effective in traffic. At city speeds, for example, simply accelerate up to 55km/h in a slow and steady fashion, as indicated in Lesson 3, and then release the gas pedal and coast down to 40km/h while the vehicle’s engine is off. Adjust the speeds for freeway application as necessary and repeat as long as it is safe to do so, ensuring that your hybrid’s gas engine turns off while you’re gliding. Start by trying to keep your pulse and glide cycles the same length (of time) and then experiment with various pulse/glide cycle durations and target speeds to see where your fuel economy is most improved. Clearly you must know your trip fuel economy in order to effectively tune your pulse and glide technique and, fortunately, most hybrids come with the instrumentation.
For vehicles that do not feature hybrid drives, pulse and glide is a technique that can only be effectively applied in some conditions. Specifically, you can really only pulse and glide at speeds where your engine will be in DFCO mode when you’re gliding, otherwise the benefits of pulsing and gliding will be lost. The best and most obvious application in a non-hybrid car would be at freeway speeds and on a clear, flat road. Pulsing and gliding in traffic and/or at city speeds may be unsafe and will not usually be effective. Accelerate modestly above the speed limit and then decelerate modestly below it exactly as you might in a hybrid. Ensure that your engine remains in DFCO mode the entire time you’re gliding or you will negate the benefits of pulsing and gliding. Obviously you will need to know both instantaneous and trip fuel economy to perfect your pulse and glide technique in a non-hybrid vehicle. If your vehicle does not have the instrumentation, then you will need a ScanGaugeII. Once again, experiment with target speeds and pulse/glide cycle lengths.
For non-hybrid vehicles that do not have a DFCO mode or at speeds where DFCO is not activated, pulsing and gliding is not likely to be effective. You might try to drop into neutral while gliding and experiment with your fuel economy, although this is not recommended because neutral coasting may jeopardize safety. In ideal applications for non-hybrid vehicles, pulsing and gliding may generate fuel economy benefits of just a few percent or up to and in excess of 10%, and hybrid vehicles may realize even more substantial gains. This is a technique that requires practice and experimentation to perfect so, if you have the gauges, invest some gas and give it a try.
Climbing Hills
Running into hills during the course of a drive is basically inevitable and, if you've ever paid attention to your car's gauges and the sounds it makes while climbing hills, you probably know that it's also a real gas pig. Climbing a hill is approximately analogous to accelerating and, for this reason, you want to avoid doing it as much as possible. Once again, that advice is good in theory but useless in practice.
So how do you climb hills effectively and in a fashion that saves gas? The answer is to use only whatever gas you need to make it to the top of the hill. Most motorists, on the face of a hill, will depress their accelerators in order to maintain cruising speed. When you're ecomiling, though, what you should do is instead maintain your throttle position and allow your vehicle's speed to fall as you climb. Don't press the gas pedal any harder than you would if you were cruising at the speed limit on a flat stretch of road.
Once again, this is a feat easier said than done. In practice, you will probably need to apply gas to climb steep or tall hills or else you'll just end up stopping and/or stalling. The key is to give it just enough gas to get you over the hill. As is the case with accelerating, you want to keep your throttle action smooth and steady when climbing. Sudden, jerky applications of the throttle will cost you money. Get to know your car and plan your climbing. You'll be an expert before you know it and you'll save money while you learn.
If you like to use cruise control while cruising, turn it off for hills or your car will accelerate all the way up the hill and spend gas in the process. Once you're at the top of the hill, you can resume using cruise control.
Now, if your hill is like most, the opposite face will provide you with a downward slope where you can take advantage of gravity and get a free ride that will last far longer than the descent itself. Your goal in descending a hill should be to build up as much momentum as is safely possible and then let that momentum carry you for as long as possible after the hill is long behind you, all without ever touching your accelerator. And, what's even better, is that if your car is a reasonably modern fuel injected vehicle or a hybrid, then this is a perfect situation in which to take advantage of its DFCO or engine off mode. Simply release the gas pedal and roll down the hill at speed. You'll use zero gas in the process.
Some people take their descending to the extreme. They might accelerate to extreme speeds under the power of gravity or slip their cars into neutral and/or turn off their engines. These techniques can be deadly and may not even offer any advantages in modern vehicles. I urge you to descend safely first and economically second. Take advantage of gravity but don't gorge on it and always ensure that you descend with your engine on and your vehicle in gear so that you are prepared for an emergency.
Hills are a nuisance that would not exist in a world designed for optimal fuel economy, but the fact is that they're unavoidable. Use the ecomiling techniques to minimize the fuel-consuming impact of hills. If your aim is to climb a mountain as opposed to a hill, then I'm afraid you're out of luck.
If you employ some advanced fuel-saving techniques, why not send us some feedback and share them?
Lesson Quicklinks
Disclaimer: It is of critical importance that you always place safety first and fuel economy a very distant second. Although ecomiling may be an engaging, exciting and money-saving challenge, never place fuel economy above your safety or that of other road users. Obey all local traffic laws.