Tow haul button
I have a 04.5 duramax 3500 and I'm not sure when to use the tow/haul button on my gear shift also using this will it help my MPG? Thanks.
Forum Discussion
n7bsn wrote:
I would suggest you read the manual, they are actually quite clear about when they recommend to use it
But no, they don't help MPG, for example, down hill they can force the vehicle into a lower gear (engine braking) which consumes more fuel
In a modern vehicle the engine enters an 'over-run' state. That is, it is moving the engine & NOT the engine moving the car. NO fuel is used. Anybody with a fuel computer that gives an instant display can see that fuel use drops to nil. BUT, as soon as the forward speed & engine/gear is matched it will start to consume fuel. This applies to both gas & diesel engines.
In the gas variant the spark plugs continue to fire to burn off any residual fuel to prevent cat damage, but no new fuel is added. This is why it is MORE efficient to engine brake and keep the vehicle in gear while going down hills than use the foot brake (risk of overheating on long descents) or coast in neutral (uses fuel to idle).
