Fuel efficiency- Stop at red light, or lift off early and don’t stop?

Ahleckz

Ahleckz

Ahleckz

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Glasgow
My partner and I have been arguing about this.

She will continue to drive up to a red light and then brake pretty late and come to a stop, causing the stop/start to come on. She’ll then sit stationary using no fuel.
I however, lift off the accelerator early and try to prevent the car from coming to a stop. Obviously I’m using fuel, but will use less when moving off/not needing to turn the engine back on.

Which is more fuel efficient? I reckon my way is, as it surely takes less fuel to carry on moving than it does from a complete stop. However, I’ll be using fuel whilst she is benefiting from the engine being stopped via stop start. On the flip side, I believe that SS is only beneficial if you’re stopped for 7 seconds. There’s probably nothing in it, but I found it an interesting question.

It’s a 2.0 diesel, no hybrid magic.
 
I'd have thought lifting and 'coasting' towards the lights - if you're in gear, you're likely using no fuel anyway and if the timing is convenient, you may be carrying some speed still and require less energy/fuel to get back to normal driving speed.
 
Lift and ‘coast’ (in gear!). While slowing (again, in gear), modern cars burn no fuel as others have said.

Less fuel to get going again as others have said but also less wear on brakes and tyres and less particulate emissions from brakes and tyres too.
 
The woman is always right. Please take this life lesson forward and thank me for the pain saved.

Say after me.. “yes my darling I’m sure you’re right”

it’s just gonna be easier!

And sorry for my horrific gender assumptions
 
I always try and taper off approach speed hopefully to avoid stopping entirely - but it is also a recommended approach by many driving instructors as it is better for controlling the traffic around you and gives you more options if an incident happens to avoid it.
 
Housey said:
The woman is always right. Please take this life lesson forward and thank me for the pain saved.

Say after me.. “yes my darling I’m sure you’re right”

it’s just gonna be easier!

And sorry for my horrific gender assumptions
Click to expand...
I'd like to retract my previous answer, this is actually the correct one.
 
+1 lifting and coasting in high manual gear if your car cuts the fuel (not all autos do)

I know many of the commute lights/sequences, so you know whether to lift your foot in high gear and coast, or continue at 50mph for best economy, and avoiding stopping.
usually don't use brakes when coming into restricted 30/40mph zones, just lift off beforehand.
 
Kenai said:
I'd have thought lifting and 'coasting' towards the lights - if you're in gear, you're likely using no fuel anyway and if the timing is convenient, you may be carrying some speed still and require less energy/fuel to get back to normal driving speed.
Click to expand...
Absolutely this.
Housey said:
The woman is always right. Please take this life lesson forward and thank me for the pain saved.

Say after me.. “yes my darling I’m sure you’re right”

it’s just gonna be easier!

And sorry for my horrific gender assumptions
Click to expand...
...but this also :cry:
 
IMHO efficiency is not the issue: your way is more comfortable as there is less sharp braking. Lift off and let the air resistance and the rolling resistance slow you down, then brake if necessary.
 
If its amber you should immediately put your foot to floor in the wain hope your car can beat the 2.5 seconds the lights are on amber. Well seems to be what everybody else does round where i live anyway.
 
don't coast in neutral (uses more fuel than in gear) for example , going down hill

Use your engine to slowly bring you to a stop / slow down
it is far more fuel efficient to roll up to the lights than use brakes, you want to "anticipate" in advance what's going to happen, so you can time it correctly without even stopping / using brakes
 
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