Which drive technique uses the most fuel.
 

I've always coasted down long hills when safe to do so, but I noticed that when I coast down a hill in my 2005 Astra I get 130mpg on the instant consumption, but 999mpg if left in fifth gear on engine braking. Presumably the ECU is cutting off fuel under certain conditions to reduce fuel consumption? Do any of the 75/ZT models do this?:shrug:

Never coast, the driving wheels should be engaged with the engine, safety!
I engine brake. I think you are right, the ecu cuts off fuel but does it only cut it down to the amount used at tick over?

macafee2

Yep never coast, always leave it in gear as the ECU will shut off the fuel supply whereas when coasting it's still using fuel to keep the engine spinning.

When coasting the engine is basically idling and using fuel. On the overrrun the fuel is reduced to the absolute minimum as it is the wheels turning the engine.

If you are learning to drive they dont teach you to use the engine as a brake. They say the brakes are alot better than years ago so no need. You often hear "brake pads are cheaper than gearboxes" and you can be penalised for unnecessary gear changes. My daughter is learning to drive and she has been taught to dip the clutch just before the car comes to a standstill and put it in first gear if she comes to a stop or needs to pull away again!:eek:

I have heard this reason before but it just makes me ask, when was the last time a gearbox was changed due to engine breaking? We have signs that tell use to use a low gear for descending hills. Your daughter may also be taught to park on the wrong side of the road, something I consider stupid and dangerous. anyway, good luck to he.

macafee2

Think I saw this on Top Gear, when going downhill in gear with no gas the wheels are driving the engine through the gearbox, so that suggests a fuel saving.

Your KV6 does Martin. Here's a quote from RAVE:

"The TP [Throttle Position] sensor also enables the ECM to provide over-run fuel cut off strategy. When the ECM receives a closed throttle signal from the TP sensor in conjunction with a vehicle speed signal which indicates the vehicle is moving, the ECM will inhibit injector operation. Fuelling is reinstated in a controlled manner when either of these parameters change to prevent [the] engine stall[ing]."

Simon

What learner drivers are taught nowadays is to "Block Change" where you brake to slow down and then go directly to the gear you then need say 4th straight to 2nd or 5th to 3rd dependant on what you are doing next. Engine braking is now frowned upon.

As an Ex Driving Instructor learner drivers were Never taught to park on the "Wrong" side of the road.;)