fuel economy
 

Still new to this car, and wondering how others drive and manage fuel economy in the TT, my mileage seems to be all over the place according to the onboard dash computer.

I know the car is meant to be driven pretty hard, but it's using like a quarter tank for 20-30 mile jaunts. That may or may not include a few hard stabs at the gas pedal, and brakes.

tips?

Buy another car if your worried about gas milage these suck it down

The fuel tank is also very small, so 2.5 gals or 30ish miles could be about a 1/4 tank

Do you guys know the full capacity of the tank, roughly?

So my estimate is not too far off, I am coming from a 2.8 VR6 where mileage was not stellar, but not like this, but I didn't factor in a smaller fuel tank as well.

64 liters. 16.9 gallons

I drive 15 miles to from work, mixed driving some traffic, open her up when I get a chance. I get 15 mpg, although i've seen over 22 on a long trip.

I get on average 18 mpg, and have hit 26 at 75 on the highway. Considering the power and fun and drivability, think this is pretty reasonable.

with a tune and hybrid turbos i'm filling up 2x a week and averaging over 1k miles a month. i can't use "fuel" and "economy" in any discussion of my car. fun, on the other hand......

03 x50 and the most i ever have gotten is 22mpg on trip to florida and back..car ran 18 straight hours on trip back to NJ.....driving the way it was meant to be driven ...around town 16mpg at best...boo hoo....but its still better that the ol' f 150 and a helluva lot more fun

i also had that triton v8 in f150 combo. THAT.. was pain.

Well, the car can be driven hard, but of course at the expense of gas mileage, at least this is often the first thing the driver notices. Tire life maybe comes in second. Or the blue/red flashing lights in the rear view mirror.

Just to give you an idea of how fuel economy can be affected by hard acceleration, my 06 GTO (6.0l 400hp, 400ftlbs torque) had instanaeous fuel consumption and under even moderately hard acceleration the fuel economy would drop into the single digits, and under hard acceleration would drop to the 5mpg range. Since the Turbo puts out a bit more hp and torque I suspect the numbers are a bit worse for the Turbo.

You can drive your Turbo hard, drive it anyway you like, but drive the car hard and you're going to pay for it in gas mileage.

Best tip I can offer you regarding gas mileage is to stay off the gas. No need to drive the thing like a little old lady or man but learn to avoid driving the car in a manner that causes the engine to make boost. Use the boost gage display to help you learn when boost is being made. Avoid running the engine at too high an rpm. I do not treat the engine like a tractor and drive it around just above idle, but I do whenever possible try to limit rpms to 3K or so with steady speed cruising a bit lower, but not too low.

Be sure the tires are properly inflated. Remove any junk from the car. Unneccesary junk just adds weight. (Types an owner who's carrying around nearly 12 quarts of oil in his Turbo's front trunk...sigh.)

If tire wear is uneven have the car aligned. Mis-alignment not only increases tire wear but this obvious friction negatively affects gas mileage. Every bit helps.

I enjoy my Turbo but manage to get between 19mpg and 21mpg out of given my usage. To help in this I try to avoid using the car for short trips unless I need to. My Boxster serves as my short trip car.

On the open highway the Turbo's gas mileage improves in some cases climbing to 26mpg or even a bit more.

Doesn't take much hard acceleration though to bring that number down and it takes even more focused driving with gas mileage in mind to bring that number up again. One hard acceleration run down a long freeway on ramp while exhilarating has that mpg display reading horribly low for miles and miles after.

If one is not careful he can introduce quite a bit of variability in the car's fuel consumption by inconsistent filling of the tank or varying when he resets the on-board computer.

When you fill up the gas tank watch the automatic nozzle shutoff. With my car sometimes the nozzle shuts off too soon and less often when I think it shuts off too soon the tank is really full to near brimming and another squeeze of the handle has gas running out of the filler neck. Some nozzles are worse than others and I have a favorite gas station at which I have learned which pumps have nozzles are less likely to early shut off and use though pumps whenever possible. On the road, I am just careful with any nozzle.

I have learned to avoid these early shut off or overflow scenarios so the tank gets filled to about the same level each fill up. In some cases when it 'feels' like the nozzle shut off early, to double check I'll walk around to the driver's side of the car and insert the key and turn the key on to update the fuel level gage's display to confirm the tank is full or still a bit less than full. If less than full I'll of course top up the tank to full. This makes the mileage numbers more consistent.

After filling the gas tank, my techique then has me getting in the car starting the engine then using the on-board computer stalk to view and write down the various data of interest to me: Odometer, trip odometer, mpg, range, average speed, then reset all readings, then taking off.

Sincerely,

Macster.

17.6 mpg for last couple thousand miles combination around town and hwy blasts. I've seen 25 on a long fast hwy run, and WAY less during 'spirited' driving...gas just may be the cheapest part of owning these cars.

I average between 13-15 mpg. I tried to be mellow on cruise control on the freeway and can get 17 or so. But.... can't keep off the boost. :) In a related note, our local fuel stations are starting to boast non- alcohol premium. That said 76 and Conaco only post 91 octane with their non-eythanol gas, compared to the 92 octane Chevron that still has alcohol. The alcohol must have some effect on the octane rating??? It seems like it would be a good thing to have 92 without alcohol.

Turbo engines, particularly older designs like the 993TT suffer a double whammy. When you are not using the boost you suffer from the inefficiency of a very low compression engine. When on the boost, well, you get to pay for 400-500 horsepower. On long road tips with Terry and his 997TT, he gets about 20% better fuel mileage then I do... cars driven EXACTLY the same. I can't tell you how annoying that is.

Im over 25mpg on the highway all the time but half that around town.

Its the price you pay for fun and its not that much different than my supercharged NSX was.

It is however irrelevant to the way my NSX went through rear tires. 1500miles and those suckers would be done. That was horrible!

The octane rating is measured/determined based on the fuel's blend. IOWs, the affect the ethanol has on the gasoline's octane rating has been taken into account.

Ethanol is an octane booster, but what this means is the ethanol is used in place of probably more expensive compounds to raise the gasoline's octane rating.

(There used to be and probably still is a federal subsidy on ethanol. IIRC, it was 60 cents/gallon which gives ethanol an unfair price advantage compared to alternatives. If this subsidy was removed and ethanol had to stand on its own in the market place, it would not stand on its own.)

Generally these engines (make that all modern Porsche engines) do better with the higher octane blends of gasoline. The Porsche engines are really designed to run with 93/94 octane and yet in many areas of the country 91 octane is the highest octane grade available.

Unless the engine reacts unfavorably to the 92 octane gas with some ethanol in it you will probably do better feeding your car's engine a steady diet of this gasoline. The higher octane will allow the engine controller to keep the ignition timing advanced more than it would with a lower octane gasoline under the same operating conditions and this results in improved driveabilty and improved fuel economy. A 'bonus' is the engine runs a bit cooler as retarded timing results in a higher exhaust gas temperature which subjects all components exposed to the exhaust gas to higher than 'normal' operating temperature.

Sincerely,

Macster.

Unfortunatley ethanol has less BTU then the same amount of gasoline, so you suffer a bit. MTBE's was the ingredient that ethanol has replaced. MTBE was the replacement for lead in pump gasoline. In order to make ones engine actually take advantage of the positive properties of ethanol, the engine has to be built and designed from boith a mechanical and electrical perspective. Fuel and advance curves are totally different than what is used in a petro burning engine, Hence the reason for less in mpg and some performance in these partial ethanol fuels. Flex fuel vehicles try and bridge the differences but only partially and really do not conform to a full ethanol only vehicle.
Ethanol does provide octane properties.

You guys seem to get worse mpg than I'd expect - is it because your fuel is lower octane?

With mixed driving (plenty of short journeys, and some blasts) I average 19mpg. On long motorway journeys I average around 28-29mpg. For it's power, I actually consider my turbo pretty economical with fuel.

At what approximate average speed?

Also, are you using "Imperial" gallons, which are a bit larger than USA gallons.

Yes, ethanol has less energy and in higher ratios can require different fueling maps and so on, but my experience with 91 octane and 93 octane gasolines both blended with up to 10% ethanol (though my info is most if not all refiners do not blend above the 7% to 8% level) is that the higher octane gasoline makes a noticable difference in the car's gas mileage.

If the choice is 93 octane gasoline sans ethanol vs. anything else then the choice is clear. Ethanol free 93 octane gasoline.

But few of us have that choice anymore.

So, if the choice is between say 91 octane even sans ethanol and 93 octane with ethanol, I believe the better choice would be the 93 octane, simply for the higher octane numbers.

Some of us do not even have the choice of 91 or 93 octane gas.

That the DME can run the more ideal ignition timing map because of the higher octane rating more than makes up for the negatives a slight bit of ethanol brings with it.

Sincerely,

Macster.

I sit at 90mph as much as I can (allegedly) but average is probably more like 70mph.

@65-70 I can get 28 depending on the weather and level road. But I never usually drive 70 on the hwy it's 75 or above.

At that average speed I'll average 22-24 mpg with EVOMS Stage 2 programming.

The small tank is the biggest issue to get used to. I get about 16 in mixed city driving (occasionally goosing it, but not pushing all the time) and upper 20's on the highway. Not bad for a high performance sports car, but if gas mileage is a big concern, get a Prius. :)

18mpg over about 5000 miles hwy and city combined. I don't baby the car but I do cruise on the hwy in 6th gear at about 2800 rpm unless I can see far enough ahead to check for the boys in blue.

This. Routinely get 26-28 on the highway if I dont stomp on it all the time.