Save fuel: Don't idle your car in cold weather.
It makes no difference!

Link to story: autos.yahoo.com/articles/autos_content_landing_pages/1650/eight-facts-about-warming-up-your-car-in-winter/

PS: Must be true because I read it on the internet.
(The Archduke of South London I'm in your Girlfriend eating her organs, Mon 10 Jan 2011, 8:49, 8 replies, latest was 14 years ago)

Some of that is a little bit illogical.
You need the engine to run for a bit so the heating matrix warms up allowing the windscreen to demist, you can't very well go driving off if you can't see.

Also, turning the engine over uses a lot of battery power, especially diesels. Stopping and starting an engine if you're stopped for more than 10 seconds doesn't seem like a good idea in a car that doesn't have dedicated stop-start technology.

A better way to save fuel is to dip the clutch and coast when on gentle inclines. Not recommended on a twisty 1 in 4 on the Yorkshire Moors when engine braking is required.
Mind you, they say don't bother with engine braking and just use your foot brake because brakes are cheaper than gearboxes.
( sandettie light vessel automatic New Twitter - @bollocksreally, Mon 10 Jan 2011, 11:19, Reply)

I engine break all the time and am probably looking at getting a new clutch soon
...after 130,000 miles. Not too bad.

Prob depends how you do it. If you ride the clutch to engine break or otherwise try to do it gently, you're probably asking for trouble. Best to pick the right gear and bang it in*

I've always been interested how much petrol a car will use to "start up", mainly because I've a mate who always bangs on about "Don't bother turning off your engine unless you're gonna be stationary for more than 10 minutes otherwise you waste more fuel than you save". I think he's misremembering something he was mistold... 10 minutes? Really? He wont budge and I have no proof.


*Also works with girls
(MrOli is ugly, but in the morning you will be sober, Mon 10 Jan 2011, 11:29, Reply)

Aha, it is, in fact, ~10 seconds.
I like this statistic. It will allow me to be extraordinarily smug when next this subject comes up at a railway crossing or some such place.
(MrOli is ugly, but in the morning you will be sober, Mon 10 Jan 2011, 11:32, Reply)

I can't think of any situation
when I would be stopped for more than 10 mins unless I was parked. Even if a bridge goes up, I've never know it take that long.
( sandettie light vessel automatic New Twitter - @bollocksreally, Mon 10 Jan 2011, 12:44, Reply)

Exactly why this argument comes up every single time...
Though it sounds like you've never experienced the joy of West Worthing station. You're not missing much.
(MrOli is ugly, but in the morning you will be sober, Mon 10 Jan 2011, 13:14, Reply)

You won't save fuel by pressing the clutch and coasting down hills
All modern cars with fuel injection (all diesels are fuel injected too) will cut the fuel supply completely on the over-run, so when using engine braking downhill you're not even using the small amount of fuel that an idling engine would consume.

Every little helps.
(WillI'mNot logs in twice a year, every year, Mon 10 Jan 2011, 11:50, Reply)

Starting.
Many cars start much, much faster than they once did.
My Micra starts in ~0.3 seconds. This is probably around 2s of normal idling fuel-wise, and the electricity used is replaced in well under a minute of driving.
(speedevil, Tue 11 Jan 2011, 16:57, Reply)

You need the engine to run for a bit so the heating matrix warms up allowing the windscreen to demist, you can't very well go driving off if you can't see.
You monster! Think of the poor little fluffeh kittehs that will choke on your exhaust fumes, just because you can't be arsed to lean forward and wipe the screen!
If it's frosty, I'll start the car before setting to with the ice scraper, mostly so I can warm my hands on the vents when I'm done but otherwise? Just have a decent, clean cloth in the door pocket, Shirley?
Your point about coasting to save fuel falls down on two counts. Firstly, as has been pointed out already, in a modern engine, taking your foot off the gas shuts off the fuel injection unless the ISCV (Idle Speed Control Valve for those who don't speak car) detects the engine slowing below it's idle point.
Secondly, and this may just be since I recently trained as an HGV driver, and had it drilled into me (fnar fnar), but you should NEVER EVER COAST, EVER! Especially down hill. The only time your foot should be on the clutch while moving is when changing gear, setting off or coming to a stop, otherwise you're not in complete control of the vehicle.
My instructor was very keen about this, and it holds true. Ever gone to change down on a gradient and missed the gear? It's surprising how quickly the speed builds up if you're momentarily distracted. If you're in the right gear, the engine braking is doing a good deal of the job of maintaining a steady speed for you.
The thing about engine braking is to use it, but don't change down until you've slowed down a bit. I was taught that 'Brakes are for slowing, gears are for going.' Iow, take foot off gas first, brakes if necessary, go for a lower gear when the engine gets to just above idle speed, before it starts driving you on.
Sorry, I seem to have gone off on one there. I wasn't trying to be a smart arse, though I'm sure that's how it appears!
(Hairy Bob, Fri 14 Jan 2011, 11:38, Reply)