Hypermiling (Saving Lots of Fuel) in a Hybrid

Hypermiling is an endless pursuit--the quest for improved fuel economy, ratcheted up a couple of notches to near fanaticism. Those who practice it are called hypermilers, a dedicated group of guys and gals who routinely push the limits of maximum fuel efficiency. It got its name from the likes of Wayne Gerdes, one of the original devotees of hypermiling, and often proclaimed the inventor of the term. Hypermiling more or less got its start with hybrids, but its not limited to them. Here, well focus on hypermiling with a hybrid vehicle. Some of the techniques can only be done with a hybrid, or, at least they make it much easier and safer--though some hardcore hypermilers perform ALL of these techniques in regular cars. We dont recommend that, but really, a lot of it is just plain common sense that can be applied to just about any vehicle and/or driver. So what are these techniques and tools that are employed so passionately by their devotees? Read on for an explanation of these FE (thats hypermileresque for Fuel Economy) tricks. Pulse and Glide (PG) This is the heart of effective hypermiling for full hybrid vehicles. Though it takes some getting used to, and its really only appropriate for light suburban and town traffic, large FE gains can be had using it. Our first successful PG was in a Nissan Altima Hybrid. This car is equipped with Toyotas Hybrid Synergy Drive (Nissan licensed it from Toyota), but our car was lacking an energy flow monitor, so we had to rely on the EV mode display and the Kilowatt (kW) meter to execute the task properly. To initiate a PG, accelerate to about 40 MPH with the engine running (the pulse part), then ease off the pedal until the hybrid system goes into EV (electric vehicle) mode and the kW meter shows zero (or if equipped with the energy flow monitor, no arrows are showing energy flow). This is the glide part. The engine is off, the electric motor is disengaged and the vehicle is literally coasting for free. When the car slows to about twenty-five or thirty MPH (depending on traffic conditions, of course) repeat the pulse part, then the glide and so on. If properly applied, this trick uses the engine only to accelerate, and it never has the chance to idle along, wasting fuel while providing no return. Forced Auto Stop (FAS) Forced Auto Stop is similar to PG without the objective of re-accelerating. In a hybrid, it is usually a matter of lifting the accelerator below a speed of approximately 40 MPH and letting the engine shut-off. This allows the car to coast to a slower speed, or come to a complete stop without the engine running. However, many conditions can affect FAS (adequate battery state of charge, hybrid system temperature, engagement of AC compressor, cabin heat, etc.) and are not always so simple. Depending upon the hardware and software controls of the hybrid system, there are ways to fool the system into FAS. Unfortunately, they are many and varied, and beyond the scope of this article. Draft Assisted Forced Auto Stop (D-FAS) This technique involves riding in the wake of a large trailer truck at highway speeds (in FAS). Its not safe, DONT DO IT. We only mention it here because it is part of some hypermilers arsenal of tricks. Driving Without Brakes (DWB) More hypermilers tongue-in-cheek terminology. We like to think of this as driving with minimal brakes, but it must be done with a good dose of common sense--its really not a good idea to take a 25 MPH curve at 50 trying to save gas. The main idea here is to not use the brakes to scrub off speed that has been achieved with energy (gasoline) spent. Anticipation is the keyword. Look far down the road to anticipate traffic stoppages, sharp curves, and signal changes and begin to decelerate or coast beforehand. The benefit is three-fold: Not only does DWB increase brake life, it reduces the number of times the vehicle must be started from a dead-stop (overcoming the inertia of a stationary vehicle consumes an enormous amount of energy), and, with a hybrid, the coasting action (regenerative braking) helps charge the battery. Ridge Riding This is the practice of driving very close to the outside edge of the road in order to keep the vehicles tires out of the slight depressions (ruts) worn into the road surface by the constant pounding of daily traffic. For most purposes, this technique is really only effective on wet roadways. Staying out of the ruts, which are filled with a thin layer of water, reduces drag on the tires and increases efficiency. An additional benefit is improved safety by preventing the tires from hydroplaning (riding on top of the water) and loss of vehicle control. Face out Potential Parking This is just plain common sense with a little bit of exercise, to boot. Search out open spaces in parking lots to eliminate the wasteful movement of backing out of a slot. Go one better by locating a spot that is on a bit of a slope, and then use gravity to help get the vehicle moving from a standstill. Sound silly? Multiply those effects over hundreds of park jobs in a year; it really does add up. Fuel Consumption Display (FCD) This is the gauge on the instrument panel of hybrids and many non-hybrids as well. Dedicated hypermilers call this the game gauge, and in many ways, thats just what it is. This device continuously calculates a vehicles average fuel consumption expressed in MPG (or, in metric mode, kilometers/liter) and displays it to the driver who can then make a fantastic game of making the average FE go ever upwards. Instant Fuel Consumption Display (IFCD) The instant fuel consumption display is very similar to the FCD, except that it displays fuel usage, just as the name implies--instantly--as it is used. The display changes moment by moment in response to sundry dynamic physical conditions: throttle off, light acceleration, heavy load, hard acceleration, coasting and cruising. This gauge, more than any other on a vehicle, hammers home the relationship between fuel economy and driving habits. Keeping the instant fuel consumption display relatively constant and even, with a high reading, will probably net more consistent (and easily attainable) FE than any trick or gadget outlined in this entire article.