Just about to get a diesel car.
We go to the village shop every morning to pick up the papers. This is about 1 1/2 miles each way. Is it cheaper to turn off the engine when we get there, or just keep it running for the minute it takes to pop in and out of the shop?
Thanks
Since your engine won't have warmed up properly after 1.5 miles it is probably best to leave it running so that is will get hot enough to reduce the deposit of acidic condensates in the crankcase and exhaust system.
WE (as in 2 of us) go down to the shop, therefore 1 of us in the car while other gets the paper. So that's that one out of the way.
Walk? Used to ten years ago when we were younger and fitter. BUT downhill all the way means UPhill all the way back. Not much fun at the best of times, and even less when walking through 2 inches of snow on top of sheet ice!
As a direct answer to your question it just has to be cheaper to switch off your engine, even if just for a few seconds. All the while it's not running it's not using fuel.
ROV1100 makes a good point, diesels might not be anything like as smokey as they used to be but it's the nasty little invisible particulates coming out of the exhaust pipe that are far more harmful to the depths of the lungs than any gasoline engined byproduct.