Is Your Car Getting Zero Miles Per Gallon?
by Union of Concerned Scientists on 01.22.07
If your car is running, but not moving, the answer is yes. Whenever your engine is idling while your car is stationary, you’re effectively using gas to get nowhere. Idling wastes money and fuel and generates pollution. Some states even have laws against idling for extended periods of time.
Idling can actually damage your engine over the long term. Because idling engines don’t operate at their peak temperatures, the fuel passing into the engine does not completely combust, leaving residue in the engine that can contaminate engine oil and make spark plugs dirty. Excessive idling also allows water to condense in the vehicle’s exhaust, contributing to corrosion.
While older cars from the 1970s and early 1980s might have needed time to warm up, the norm since the mid-1980s has been fuel-injection vehicles which can be restarted frequently without engine damage.
When you start a car’s engine, a little bit of extra gas is used to get the combustion process started. That means a good rule of thumb for conserving gas is to idle for no more than 30 seconds, except, of course, if you’re just sitting in traffic.
If you have a hybrid car, it does the work of avoiding idling for you. While parked or sitting in traffic, hybrids shut off their gasoline engines automatically. See also: ::Citroën C2, Now With Stop & Start Technology
Where did you get your information.
Engine wear due to stop and start has nothing to do with carburation vs fuel injection, it has to do with lubrication. When the engine starts, it takes a few minutes for the engine oil to warm up and flow over all the engine's wearing surfaces. Because of this delay, the majority of engine wear actually happens in the first few minutes after being started.
I recall a recent lexux model had a different automatic transmission shifting profile for the first few minutes after starting, to prevent the engine from spinning at over 3000RPMish to minimize this wear.
Yes but that's only for the first time you start it. If you turn it off after that, it stays relatively hot for a while, so there's no reason to keep idling for short periods of time (and even less reason to idle for long periods...).
Unfortunately, in colder states, we need to warm-up our cars come the winter. It is not good for a car to be driven as soon as you start it up when the temps are below 0 degrees.
SO....although I agree with the idling issue. Come winter time (especially in VT,) idling is something we all are almost forced to do....
Not true. Modern cars are warmed up in seconds.
Click and Clack talked about this a couple weeks ago. The best way to warm your engine is to drive it. As for idling, modern fuel injected engines could idle all the time and not cause damage to the engine.
So start it up and go.
And when you get there...well let it idle. LOL just kidding shut it off.
The most inefficient time for a vehicle's emissions system is at startup. The catalytic converter (and additional equipment in a diesel engine) are almost completely ineffective for a period of a few seconds at startup, causing severe emissions releases. Unlike the engine, the emissions system cools down rather quickly, maybe 15-50 seconds depending on the actual vehicle.
Shutting down the vehicle rather than idling for 30 seconds will save an insignificant amount of fuel. Yes, the car won't pollute for those 30 seconds, but the large release of pollutants upon startup will by far negate any benefit. Perhaps more reasonably, cars should be shut off if they're going to be idling for more than 1 minute or more, and even then the benefit is questionable.
You would really have to dig into the numbers and calculate the savings in emissions by turning off the vehicle for a certain amount of time vs. the negative effects of startup - and also the fuel saved when turned off vs the fuel consumed upon startup. It's something that will vary with each different vehicle, and when it really comes down to it, in anything less than maybe 2-3 minutes of "idle vs. off" the benefits are rather negligible compared to the hundreds of other things that you can do to much more drastically reduce emissions and fuel consumption.
Erhm:
switching off your engine at traffic lights which are known to have long phases of red.
In some countries there are indicators signalling the driver that it is still useful to switch off or to keep the engine running depending on the time of red phase that has passed.
Regards,
AC
"Not true. Modern cars are warmed up in seconds."
Sorry man, but you are blatantly incorrect. Take a look at your temp gauge when you start your car next, and count the minutes until it moves. Chances are it will be about 5 minutes before it hits 1/4 of the way up. Even brand new cars cant overcome the basic laws of science.
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editor note: Warm enough to drive, but not at peak temperature, obviously.
Heh, in 10°F and lower weather, I start my car up (Mazda 6, 2003) and drive to work without starting it up to let it idle.... In the matter of 5 minutes I am getting hot air in my cabin.
Glory be to the aluminum engine block!!
I'm all confused, some people say yes idling is good others say no its bad and pointless, but then why is it that when i start my car, which by the way is a 2001 toyota, a modern car to put it on those terms, when i start it it starts rough and as a matter of fact when i look at the rpm's the needle is actually hovering over 1,250 or so rpm's without any influence on my part. And if i put it in drive the car feels like its running "roughly" than usual as it would if i would have let it warm up.
if i get zero miles a gallon does that mean i waste fuel without moving?