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

[Ahleckz]

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.

 

[Ahleckz]

Right, so we’re all agreed that naturally slowing and not stopping is the way to go.
Surely though if the engine is on, and turning over then fuel is being used? So even coasting in or out of gear, is still using some fuel?

However, at what point does it make sense to stop? How long would you need to be stationary, using stop start and thus having the engine off to compensate for the fuel required to get going again?

 

[Ahleckz]

Both of you are doing it wrong, stops at red lights should be approached gently then the brakes applied sufficient enough to allow the start stop to operate. I do this all the time so it is definitely possible.
Thus not only saving fuel but also allowing the start stop to do what it is intended to do and help in reducing pollution when stationary...

But you’re then using fuel to restart from Stationary, which may undo all the good you’ve done!
Unless you’re saying your stop start kicks in whilst the vehicle is in motion. My one doesn’t (Mercedes GLC).