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Wednesday
Jun032009

Pulse and Glide

I've been learning about "pulse and glide".  This is a technique used by dedicated hypermilers like Wayne Gerdes at cleanmpg.com to dramatically increase gas mileage.

Pulse and glide (P&G) is a bit unintuitive.  I had always assumed the best way to get good gas mileage was to maintain steady yet light pressure on the accelerator, keeping the revs low and allowing the car to slow down going up hills and speed up going down.  The idea behind P&G is that you drive within a range of MPH, say 30-45 mph.  First you accelerate to the upper limit (the "pulse"), then you release the accelerator somewhat and "glide".  You try to maintain an average MPG figure that's higher than normal.  For instance, if you pulse for 20 seconds at 15mpg, then glide for 20 seconds at 45mpg, you should get 30mpg during that P&G cycle.  You need an instantaneous mpg readout to do this.

To increase mileage during the glide phase, avid hypermilers will put the car in neutral during the glide.  By putting the car in neutral you can keep engine revs low and eliminate engine drag.  This means that you must put the car in drive again before the next pulse, which depending on your car may require you to match the revolutions of your engine with the car's speed.  The FFH does not require rev matching because of the transmission design.

The FFH doesn't have engine drag at low speeds; however when you lift off the accelerator below 47 mph the internal combustion engine turns off and the electrical engines go into battery regeneration mode which simulates engine drag to the driver.  You can add gas pedal pressure to reduce the amount of regen / drag but putting the FFH into neutral can reportedly give you a longer glide.  The downside is that in neutral there is no regen available even through braking.

I've tried P&G with my Audi A6 (although I usually don't put it in neutral during the glide). Its a difficult technique to use in traffic or stop and go conditions such as I have on my drive to work. I think it does increase mileage but only when I'm paying attention! That's the main issue - P&G requires a lot of concentration and dedication; and it can be frustratingly slow.  I'll report on P&G in the FFH once I get mine.

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Reader Comments (1)

This technique seems legit and increasing gas mileage would also mean that the value of your car.
Doing this correctly would have a great output on your car.

March 31, 2012 | Unregistered Commentergarage equipment

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