Pulse and Glide, Burn and Coast

Burn and coast is also known as pulse and glide.

 

This method consists of rapid acceleration to a given speed (the “burn” or “pulse”), followed by a period of coasting down to a lower speed, at which point the burn-coast  sequence is repeated.

Coasting is most  efficient when the engine is not running, although some gains can be realized with the engine on (to maintain power to brakes, steering and ancillaries) and the vehicle in neutral, or even with the vehicle remaining in gear.

 

If a manual transmission vehicle coasts with the engine off¹, it is typically restarted by disengaging the clutch².

The engine control units of some vehicles command a richer fuel setting immediately after the starter is activated, so the bump-start  manual transmission vehicle will typically achieve the best  fuel economy gains.

 

Some hybrid vehicles are well-suited to performing the burn and coast. In a series-parallel hybrid, the internal combustion engine and charging system can be shut off for the glide by simply manipulating the accelerator. However based on simulation, more gains in economy are obtained in non-hybrid vehicles.

 

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Pulse and glide is a driving technique that is designed to make your driving more fuel efficient.

It is most often associated with hybrid cars and cars that have a manual transmission system although most cars can work on this technique with a bit of practice.

To make this manoeuvre you will need to accelerate your speed to a designated level - this is known as the pulse here. You can then use the car to coast for a period - this is known as the glide. When you enter the glide period of this manoeuvre your engine will technically not be working and you will be coasting on the acceleration you did as part of the pulse manoeuvre. The aim here is to keep repeating the pulse and glide manoeuvre as you go along.

The way that this manoeuvre works is based on the fact that you will initially drive a little faster than you want to when you pulse before then coasting at a slightly lower speed than you want to when you glide. This will give you the kind of average speed that you were aiming for in the first place and you’ll save fuel rather than just driving at your desired speed in the normal way.

 

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An alternative to acceleration or braking is coasting, i.e. gliding along without propulsion.

Coasting dissipates stored energy (kinetic energy and gravitational potential energy) against aerodynamic drag and rolling resistance which must always be overcome by the vehicle during travel.

If coasting uphill, stored energy is also expended by grade resistance, but this energy is not dissipated since it becomes stored as gravitational potential energy which might be used later on. Using stored energy (via coasting) for these purposes is obviously more efficient than dissipating it in friction braking.

* When coasting with the engine running and manual transmission in neutral, or clutch depressed, there will still be some fuel consumption due to the engine needing to maintain idle engine speed. While 반면에 coasting with the engine running and the transmission in gear, most cars' engine control unit with fuel injection will cut off fuel supply³, and the engine will continue running, being driven by the wheels. Compared to coasting in neutral, this has an increased drag, but has the added safety benefit of being able to react  in any sudden change in a potential dangerous traffic situation, and being in the right gear when acceleration is required

Coasting with a vehicle not in gear(=in neutral) is prohibited by law in most US states.

1. 엔진을 끄는 것은 절대로 안된다. 매우 위험한 발상이다. clutch를 밟으면서 내려가는 것은 가능하다. [본문으로]
2. 클러치를 밟음. [본문으로]
3. ????? Electric Control Unit 에 이런 기능이 설계되어 있는 경우에만 연료공급이 중단된다.. [본문으로]