Gas Mileage - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Richard Truss · 03-31-2005, 10:51 PM

It seemed as thought I was filling up a lot -- like over once a week. So I finally filled up, reset the trip and drove average -- sometimes mellow, often really gettin into the gas. But the next time I filled up I was in horror to see I got an overall average of 15.3 MPG!!! I did a search on this board, and this seems far far lower than most experienced -- even with the 3.2 (that i own). No CE light, car runs great....

what kind of mileage are you all gettin? and if mine sucks as much as i think it does, where do you think my car is eatin all the gas? at $2.60 a gallon here in vegas, i will go broke at this rate.

PAH · 04-01-2005, 02:40 AM

$2.60 a gallon - you poor thing! (Hint of sarcasm!)

I paid £4.09 per gallon this morning, which is what....not far or $8.00 per gallon!

I am getting about 24 MPG driving normally in my 3.2 (without flooring it), so you do seem to be using a lot of fuel.

Just in case US gallons are a different measure to UK gallons (can't remember) - I'm getting about 320 miles from a full tank of fuel.

Brucelee · 04-01-2005, 06:13 AM

Well regarding the higher price of gas in Europe, you might ring up your elected officials and suggest you have had it with the whole tax thing!

Back to the MPG issue, it does seem like the 15.6 is low but the again, if you are sitting on the strip in Vegas on Saturday night, that is not that bad.

Ditto, blasting through the desert at say 110 MPH.

If you are doing 70 MPH steady, you have an issue. My Box S's usually will get 25 or so at steady highway speeds. Much less in town of course.

Hope that helps.

dennizxxx · 04-01-2005, 07:20 AM

i'm getting about 17-18 in the city and about 21 on the highway.....although I'm not the most conservative driver...and I drive it in the city a lot...

Perfectlap · 04-01-2005, 07:20 AM

18 mpg tops for me. Lots of of stop and go city driving.
I rarely use 4th gear, let er rip!

But I have massively cut down on Launching the car from a stop. It becomes
such a habit you don't even realize that its not normal to have three blocks
between you and the car's you were just with at the stop light.
Not to mention its horrible for rear tire tread life.
I try to make the upshifts as smooth and commotion-less as possible.
Like if I had a passenger he wouldn't be able to tell the difference between siting in my BoxsterS and automatic SLK.

But launching the car was too much fun at first. That Miata I was nice but...
http://www.thephatphree.com/features.asp?StoryID=293&SectionID=11&LayoutType=1&StoryMonth=3&StoryYear=2005

RandallNeighbour · 04-01-2005, 07:52 AM

I'm getting about 18 mpg on long trips... I drive 90 mph as often as I can though, and I'm confident this is the culprit. I just fall asleep in this car going 70!

Ah, long Texas highways are good for something, huh?

15 sounds really low though.

Thumper · 04-01-2005, 01:03 PM

I have yet to take a long trip in mine, but I'm getting 17 - 18 mpg around town. I have trouble staying below 85 or 90 on the highway.

:dance:

Richard Truss · 04-01-2005, 06:50 PM

well, i dont make it a habit of going to the strip, BUT i will say that i drive surface streets WAAAAAY more than freeways. we only have 3 major freeways in vegas -- all of which are always packed with crazy people. But it does sound like 15 is low.

what do you guys think it could be? where should i look first? i dont really smell any fuel or see any leaks....

Brucelee · 04-01-2005, 06:56 PM

Fuel Filter, Air filter, Tune up (read plugs) O2 Sensor are my candidates.

Tire Pressure too! Assume you are using Mobil 1 black cap.

Richard Truss · 04-01-2005, 07:26 PM

i will check all those things. i know the air filter is due to be replaced and i have not checked my tire pressure for a while. i just got a new MAF -- is that the same as the O2 sensor?

as for oil, i am currently using mobil 10/30 -- would that be the correct weight?

Cecil Suzuki · 04-02-2005, 12:48 AM

Nice full-throttle run outta of the SF Valley, but the 101 was bumper2bumper through Oxnard and Ventura. Way back into the Valley was crowded but real fast 'cept for slowdowns from Woodland Hills on in.
Left Burbank with about a half a tank, returned with the little red light on---approx. 24.3 mpg.

Brucelee · 04-02-2005, 05:31 AM

Quote:

Originally Posted by Richard Truss

i will check all those things. i know the air filter is due to be replaced and i have not checked my tire pressure for a while. i just got a new MAF -- is that the same as the O2 sensor?

as for oil, i am currently using mobil 10/30 -- would that be the correct weight?

No, the O2 sensor is different sensor. Sits back of muffler. If it were bad, you would get a code.

Re: Oil, manual recommends 0-40 Mobil 1, which I would certainly recommend in your Vegas summers. In winter you could get away with the 10-30 Mobil 1.

Another alternative, which is less expensive, is Shell Rotella T, full syn. 5-40W. Run it all year long.

Wally World at $13.50 per gallon.

donv · 04-02-2005, 08:05 AM

22.27 avg. MPG delivery to date including track days, autocross, regular and hot foot around town and highway driving, etc.

Richard Truss · 04-02-2005, 09:58 AM

well i just changed my oil, so my next change i will go to 0-40w. thanks for the tip. ANYWHERE in the 20's seems like a gift right now. I will go through everything -- starting with the air filter -- which i guess it is about time i actually see my engine, so this will be good motivation.

so the filters and O2 sensor -- is that something that a tenatious novice mechanic could do? and is there any where i could get the filters and the like (i.e. outside of the dealership)? or should i go there (i get my oil filter at the dealership).

Thanks.

Adam · 04-02-2005, 10:31 AM

i changed the air filter and I have very limited abilities. Have you ever accessed the top of your engine before? If not, check your manual.

Richard Truss · 04-02-2005, 03:12 PM

nope, never accessed the top of the engine before. i will check the manual, also i know there have been good write ups on here how to do that. I did check my tire pressure -- no surprise, they were all severely low. according to the tire, they should be filled with max 51 psi (that seems high to me, but then again i have never had a car/tires of this caliber). all the tires were somewhere in the 30 psi range. so i filled em, reset the trip and see what happens. i will try and get an air filter this week and maybe install it next weekend.

Adam · 04-02-2005, 03:48 PM

Don't fill them to max PSI! lol Porsche reccamends 36 psi in the back and 29 psi in the front. This setup tends to make the car push more in turns though. I go with 36 in the back and 32-33 in the front to make the car more neutral in the turns. The more air you add in the front, the more oversteer you will get. If you are going to do any auto-x or track work raise by 5-10 psi.

If you are going to get a new air-filter I would reccamend you purchase a BMC F1 air-filter. It costs about 70 dollars. I've had mine for a year now and have experienced no problems. It's supposed to add a couple hp. It is similar to the K&N but less oily and made of higher quality materials. The K&N's are known to cause MAF problems.

Adam · 04-02-2005, 04:15 PM

This is where I purchased my filter. Some places list it as high as $120 so you probably can't beat this deal.

http://shop.store.yahoo.com/eagleday/pobmcpefi.html