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Discussion Starter #1
I'm not really asking for an exact quantity. But sometimes I have those situations where I can either let the car idle for a few minutes, or I can turn it off while I wait then start it up again.
 

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I have always heard better to idle for short periods but with the enviromental issues and the car thiefs I shut mine down unless it is bloody cold.
 

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idle is 700rotations per minute

startup jumps to what? Ill say 1700rpm, so thats 2.4times faster than just idle so 2.4% more gas. So idle for 2.5min would equal that of a start up. ( I think that made sense)

Id say unless your sittingin a solid 4-5min leave it on. Of course everytime a train drove by I turned my truck off, but then again how can you not enjoy the startup of a modded v8 with exhaust?
 

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Discussion Starter #4
is gas consumption really that direclty related to RPM? wouldn't the engine work less to keep it at 700?
 

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[quote author=Uggie26 link=topic=66198.msg1136135#msg1136135 date=1168108544]
is gas consumption really that direclty related to RPM? wouldn't the engine work less to keep it at 700?
[/quote]

yes...each time the piston goes up and down, another "shot" of gas is placed in the cylinder. If you put the engine to 2k RPM, you're shooting in twice as much gas as if the car was at 1k RPM
 

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Typically a good estimate is the amount of gas it takes to start the engine is equal to the amount of gas used during one-minute of idling.

So if you are idling more than one minute, you'd have been better off just turning the car off.
 

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I have a gas station down the street from where I work. When I pulled into work, it was on e, the light had been on for a while, but I was running late. i had no choice but to park it in one of the dozens of parking spots I normally park in.
Come lunch hour, I started the car, on E (it couldn't go any further) and let it idle while cleaning off the car, then casually drove it to the gas station, and filled it. It normally never goes down past 3/4 a tank. But still, I've had a job at a ford dealership before. Lots of cars will remain running for quite a few miles past empty.

Ever watch Seinfeld? It's true.

Mind you, if you have some freaky fuel guage and end up stranded somewhere, don't take my word for it. ;)
My story, however, of what happened to me today is true :D
 

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I think it actually takes a lot more to start the car.
I am probably wrong, but i do think that the reason i get crap MPG (18mpg city, 25 highway) is because i usually start the car like 5-6times a day.
 

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As I understand it, with modern fuel injection there's very little fuel waste when starting. Don't all those hybrids constantly stop and restart?
 

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I think our cars have 15 miles driving 60 mph once the light comes on...I THINK...if I remember correctly.

With the hybrids stay on. But at lower speeds only the electric motors are working and the gas engine is at idle. Once it does above a certain speed, the throttle on the gas begins to open.
 

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I don't know about 2.3 cause I have a 2.0, but when the E light comes on and I fill up righ away, its usually about 12 gallons. Our tanks are about 14.5 gallons, so your 3 is drinking gas like crazy if you can only do 15 miles on 2.5 gallons. On one highway trip I did about 55 miles on E and when I filled up it was about 13.5 gallons, so I still had plenty left. However I don't do it often, as road conditions may change an you can get stranded, especially in winter.
The point is you can do a lot more than 15 miles when E light comes on.
As far us starting the engine I think that only cold start-ups use more gas, as the engin is in open-loop. When the engine is fully warm the RPM jumps to 1700 for a second or shorter, and come down to 700 ( at least on my car), so if you think youre gonna idle for more than a minute and you want to save gas shut down your engine.
Hybrids do shut down the engine when you are at a complete stop, when you lift your foot of the brake, the engine starts automatically, and they would not do that if this method wasted gas. Now freaquent startups will put extra wear on your starter, so I use better judgement. Sometimes it is better just to let the car idle if it is really a short stop.
 

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Actually the prius I test drove a few weeks ago didn't start the engine until I was going ~10mph
 

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[quote author=saluteTOme link=topic=66198.msg1152062#msg1152062 date=1168958392]
I think our cars have 15 miles driving 60 mph once the light comes on...I THINK...if I remember correctly.


[/quote]

thats false. highway you have about 70-90miles til your empty (30mpg)
 

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It's true, the gas light comes on between 11.5 and 12 gallons, so you should have between 2.5 and 3 gallons left. That is at least 60-90 miles of driving at 30mpg and for the sake of argument, thats still 50 miles if you get less than 30mpg.
 

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Discussion Starter #18
this is great and all but how hell did we get to talking about how much gas is left when the light comes on?

Oh I see, it was Evil dead fan with his awesome story. But yeah, the light coming on shouldn't make you freak out. I've gone to school and back with the light on, and I live pretty far from school. They should have made it so it turns red when you only have like 10 miles left.
 
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