Pulse and Glide?

[bates]

The theory works basically by the idea that you accelerate for a realtively short period of time then coast for a realitvely long time before accelerating again. In most modern fuel injected computer controlled automotive and truck engines when the throttle is closed (your foot is totally off the accelerator pedal) and cruise control is not operating will completely shut off the fuel delivery to the engine. So basically you are burning zero fuel for your coasting sections so if you can accelerate, admittedly buring more fuel than in a steady state cruise, for a short time say 15 seconds from 50 to 65 MPH on the freeway, then you coast for 45 seconds from 65 to 50 MPH. Then you do it again. You should see a fair increase in mileage from this tactic. Unfortunately it is somewhat dangerous and not very practical for most drivers in urban or suburban areas due to traffic congestion. It will also take you somewhat longer to travel the same distance as driving at the median speed would as it takes longer to decelrate than it does to accelerate, hence the fuel savings realized. Finally it isn't the best method for prolonging your engine life when the fuel is shut off the amount of oil lubricating your engine parts is substanitally less than it is a cruise RPM (oil delivery is a linear function of RPM from a cam or crank driven oil circulating pump) so bringing on the power will cause some additional wear to those parts when the engine goes from 700 RPM up to 2,500 RPM as soon as the accelerator pedal is depressed. Also this tends to be hard on the cylinders and head since they cool substantially during the coasting segments and reheat rapidly during the acceleration segments. Thermal cycles are very hard on internal combustion engines and can substantially reduce their life expectancy.