So today Chevy said they are coming out with a cruise diesel. Mazda is supposed to bring the diesel “6” to the us as well… in my current job I drive around 25-30,000 miles a year and work from my car. This means that during the summer I will be sitting with the car at idle with the AC on while doing…

“because you can run the Ac without the gas motor running.” Now I don’t believe that would be a good idea.

You’ll use gas in a Prius sitting there. I do that in my MKZ hybrid, it turns on after the battery’s depleted below a certain level. No free lunch. I imagine a small diesel would use about the same amount of fuel. It’s driving where the vast majority of fuel is used in either case.

@texases , yes, the engine uses more fuel to move the car, but sitting at idle the gas mileage is zero. That really drags down the mpg average.

Just curious, but why would it be a bad idea? I suppose the motor that runs the compressor could wear out sooner, but that is probably cheaper than idling the gasoline engine. Is there some other problem?

I’m sure you guys are right, but this seems to contradict the advice frequently (and consistently) given here: It does NOT make sense to switch off engine when stopped at traffic light (or coasting downhill). (But maybe your traffic light stops are shorter than here in the DC suburbs, where the loc…

@MarkM : The motor that runs the compressor will wear at the same rate whether the gas engine is on or not. I can’t imagine that this is any less reliable than a belt-driven compressor such that non-hybrid cars use. You will use the same amount of energy either way. As others have mentioned, when…

Diesels of all sizes use less fuel at idle because there is no throttle and no intake vacuum for the engine to work against. They use so little fuel that keeping the engine warm at idle can be an issue in cold weather.

Fuel burn at idle is very small, whether a diesel or gasoline engine is involved. With both, the throttle plate is almost fully closed, allowing only a very minimal amount of air to enter, and in both, the pulsewidth of the injector spray will be minimized to maintain a proper ratio with the volume…

Guys, Guys… Very often you all get carried on an argument and forget to answer OP’s question… Gsragtop, idle fuel consumption for most gasoline powered 4cyl cars in good working condition is 0.8 liters per hour with A/C off, and about 1.1 liters per hour with A/C on. I came up with this figure bec…

Fuel consumption at idle

Maintenance/Repairs

Caddyman February 8, 2013, 9:07am 5

You must realize that your “engine” is not not very efficient…It would make a pretty good furnace. 70-80% of the BTU’s you buy in the form of diesel fuel or gasoline are used to heat the atmosphere not power the vehicle…So fuel burn at idle is more than you think because only 20% of it is making the crankshaft spin. The rest is making the water boil and the exhaust pipe glow…

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Fuel consumption at idle

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