jordanturbo

For those of you that actually have winter weather and drive your pcar in it, what kind of milage do you get in normal months versus winter months?

Normally I get 400-430km per tank of gas, now that winter is around, temps are low, and I have to let my car idle for 5-10 min before it hits low idle and I move the car, I am now averaging 300-320km per tank so I am down about 25%.

Ubermensch

Why are you letting it idle to warm up? Porsche is pretty specific that the best way to warm the car up is to drive it. They do not recommend letting it idle. I get in, turn the key, and drive away...

If your drive is short enough that the car doesn't warm up then you'll see an impact in your mileage since the engine is less efficient when it is outside its normal operating temperature range. Otherwise your mileage should be pretty similar (if you stop letting it idle...)

Shark Attack

I dont know.. But I swear my car runs so much better in cold weather. I dont mean smoother. I mean faster. A change I can feel in the seat on my pants...... and thats is worth 50% worse MPG

BruceP

Just took a look at my fuel economy app, and it looks like temperature makes little difference in my 996. This is by contrast to my truck, for example, which immediately starts burning a liter more per hundred km when the temperature drops to freezing, without fail.

Whereas the speed I'm driving the Porsche at makes a HUGE difference. I've seen 9l/100km and less on the highway, and as much as 18l/100km in city traffic... which is just awful.

9964runner

...and it is. cooler air is denser, denser air contains more oxygen by volume. More oxygen in, more power.... this is the theory CAI's are based on.

Imo000

The denser airnis harder to push so, air resistance is up and so it fuel mileage. Also, the additives the refineries put in during winter, to keep their gas from gelling in their fuel depos, probably lower the mileage too.

Macster

Are you sure about that 5 to 10 minutes to idle before idle speed falls to near normal?

Can't believe it would take the engine 5 to 10 minutes to fall back to near its normal hot engine idle speed.

While I do not often (anymore) get a chance to start my engines in real cold temps in either car the engine idle speed drops from around 1K to just under 800 in around a minute (or less) idle time.

Since one car (the Boxster) is outside I have to let the engine idle longer to warm up the heater and clear the frost (Sunday) but today even though it was cold there was no frost and I was away in the car after the usual one minute or so idle time, just until the idle speed dropped and the secondary air injection pump shut off.

Over the years gas mileage drops in colder weather by not quite 10%. Say the Boxster averages given my usage around 23mpg winter with the same driving route, and so on, has this down to 21.5mpg.

Anyhow a combination of things contribute to the increase in fuel consumptoin in the winter months. More idle time mainly to wait for the heater to warm up and the frost to melt but sometimes from heavier winter traffic. The engine is colder and takes longer to warm up so the oil is thicker and there's more lost to the thicker oil's friction.

Generally winter traffic is consistently slower traffic too so the car spends more time idling at lights and when moving moves slower than in the summer months.

Which brings this up: I have no kids but for those people that do and give the kids a ride to the bus stop or to the school or to after school activities obviously this change in usage can play a role.

Be sure you check tire inflation pressure. When cold temps set in tires that were inflated just fine for the warmer temps are very likely under inflated for the colder temps. Under inflated tires can really impact fuel economy.

Last while I too notice that the engine seems to pick up some in colder temps this alone can't account for the increase in gas consumption. But of course I do rather enjoy the benefit of colder temps in this regard. Cool but not real cold days, low humidity oh yeah baby I feel a few more horses straining at the harness....

jordanturbo

I looked at it a few days ago, after being parked outside for 12 hours in -19 deg C (-2 deg F) I would turn it on and it would idle at just under 1100rpm. after just under a minute it would drop to about 900rpm where it would sit for just over 2.5 minutes. from there it leveled off for about 2 minutes at 800rpm then it would drop to 5-600rpm, its low idle over the next 1 min. I know porsche says not to let it idle, but before my engine gets warm it seems to not perform nearly as nice (once it is warm it is awesome). I believe that in temps that are this cold the viscosity of the coolant and oil are high and not optimal, therefore wont circulate as well as they normally would at optimal temps. Also if I dont let it idle i wont hit the normal coolant temp (around 80deg) before i get to work which is an 8 minute drive away.

BruceP

With a commute that short, the best you can do is choose between two evils. I think in your situation, I'd probably let it warm up sometimes too, even though it's ordinarily a terrible idea. If your coolant is just warmed when you arrived, you can be sure the oil isn't.

5CHN3LL

You people actually know what kind of mileage you get? That's impressive. Mine is horrible, but that's self-inflicted, so I don't bother calculating. I just keep feeding it premium.

MiamiC70

This! Who cares, LOL

KrazyK

Who buys a Porsche and worries about fuel mileage?

babylonboots

+1

I have no idea what mine gets. Drive time is Priceless.

Huck1974

I just burnt my first tank. 16.7 mpg. I could care less about what it gets, but I had reset it when I got it and was playing with buttons. lol

Macster

Well, I have to admit that -2F is a bit colder temp at which I have ever started my Turbo. IIRC the coldest was one AM in Flagstaff where the temp was in the mid-teens.

While I do not recall the engine acting odd, requiring a long idle time, etc, I do not recall now how long the engine idled or at what rpm it idled at so maybe your engine's behavior is normal.

If so then to be sure gas mileage will surely suffer.

The coolant's viscosity is really unaffected by its temperature unless the temp gets so low that the coolant's freezing temp threshold is crossed then the coolant is just slush at best. A real risk is destruction of the water pump impeller.

Oil viscosity cold though plays a role. I would think running 0w-40 oil would be a necessity given the cold temps where you are.