I just read an article about Hypermiling on CNN.com. Hypermiling is fuel economy maximizing behaviors – for any vehicle type. Where I agree with Mr. Gerdes that many behaviors can be modified to increase fuel economy, the article does not at all mention the pitfalls to some of these methods. Before everybody maxes out their tire pressures and keys off at every stop – a few things should be noted.
Regular maintenance and smooth driving can make the biggest difference in your gas mileage! While the former is touched upon, by the brief mention of changing filters, the later was not addressed at all. Smooth driving is easy:
Generally fuel economy is maximized when acceleration and braking are minimized. So a fuel-efficient strategy is to anticipate what is happening ahead, and drive in such a way so as to minimize acceleration and braking, and maximize coasting time. Gentle acceleration and deceleration is helpful in avoiding unnecessary acceleration. Wikipedia
I would also add that using cruise control to maintain consistent speed is a surefire way to save fuel (edit)as long as you are on flat terrain. When it gets hilly, turn off the cruise and accelerate smoothly to maintain speed. If you are driving an automatic, use minimum increments of throttle so the transmission does not select a lower gear – do this to reach your cruising speed before you select “resume” from the cruise control as well. As for the rest…
Maxing the tire pressure: while inflating the tire pressure to the maximum rating on the tire will not damage the tire itself, irregular wear is the inevitable result. Given the price of most OEM tires, especially run-flats, you have to weigh the fuel savings with the possibility of premature tire replacement. A new set of 4 tires can easily run more than $500 installed – you might want to calculate at what point the savings are nullified. I prefer to keep my tires 2-4 psi above the manufacturer’s recommended pressure for everyday driving, and boost it 10-12 psi above for long distance highway trips. Tire pressure can also dramatically change traction in adverse conditions – something to consider for driving in rain or snow.
Forced stop is the practice of keying off the engine at every stop and even while coasting. While it can be argued that the driver has less control with the engine off, again, my concern leans more towards the maintenance side. It can be detrimental to the gas mileage as well as the internals of the engine if the car is not up to normal operating temperatures when this method is employed. It will also accelerate starter wear. While I’m sure starters have come a long way over the years, they were not designed to start the car 20-50 times a day. Thats over 10 times an increase in starts per day assuming 3 trips. Modern cars with stop-start technology have been designed from the get go with more robust starter motors. Again, one must weight the cost and headache of a possible starter replacement with fuel savings.
What gives me hope is the influx of stop-start vehicles in the future; with the 9% fuel savings that the stop-start equipped European Mini claims, the technology can’t come soon enough!
Low Viscosity Oil is another item requiring an informed approach. Low viscosity oil can break down under high temperature environments and cause severe damage to engine components. In temperate climates and low engine load conditions this may not be as much of as concern.
All of the above methods will conserve fuel – but what needs to be considered is at what point is it worth it for you.
Added more info to cruise control usage – I had glossed over that originally, thanks to the comments for bringing it to my attention.
NPR just ran a story on Hypermilers this morning. The more extreme methods of Hypermiling are not discussed (other than rolling through stop signs). The fact that Curtis Adam’s wife drives separately negates the whole idea!