Very low mpg, help plz

[Giller]

I think OP should check his math. Based on what he has said, no leaks, no odours - it might just be bad math? 16 mpg is quite low. He hasn't answered Monty's question about total miles driven per/trip. If it's start, short drive then stop, that will impact economy more than anything really.

[NewArt]

My 01 S is a tip. I get around 24-25 on the highway but generally around 12 around town (Montreal, stop and go, like any big city). Does anybody with a 3.2 tip get those 20 mpg figures with inner city driving? I don't think so.

[Mike689]

Originally Posted by Giller

I think OP should check his math. Based on what he has said, no leaks, no odours - it might just be bad math? 16 mpg is quite low. He hasn't answered Monty's question about total miles driven per/trip. If it's start, short drive then stop, that will impact economy more than anything really.

I got 16 for sure. I'll be refueling and calculating again in a couple days.

Originally Posted by NewArt

My 01 S is a tip. I get around 24-25 on the highway but generally around 12 around town (Montreal, stop and go, like any big city). Does anybody with a 3.2 tip get those 20 mpg figures with inner city driving? I don't think so.

I drive mostly on the freeway though. I should at least get 20 mpg.

[herve_g]

Originally Posted by NewArt

My 01 S is a tip. I get around 24-25 on the highway but generally around 12 around town (Montreal, stop and go, like any big city). Does anybody with a 3.2 tip get those 20 mpg figures with inner city driving? I don't think so.

I get about 16 mpg in Montreal, 26 to 28 mpg outside the city though, in a 3.2

[jdlmodelt]

Originally Posted by Mike689

Hello I just bought a 01' Boxster S about 2 weeks ago. I changed the oil a few days later and I drive at around 3k rpm. I'm still only getting about 16 mpg and I drive mostly on the freeway. Am I doing something wrong or is it the car? and how do I fix it? thanks!

I live in Colorado, 6200+ft elevation, I can typically only get 91 with ethanol. A station nearby recently started offering 91 without ethanol! Yay!. I get about 28.5 hiway with 91 ethanol and 30.5 with 91 non ethanol. I'd make sure your MAF sensor is clean. Of course fresh spark plugs don't hurt if its been a long time.

[fatmike]

Welcome to Porsche ownership.

Get yourself a custom license plate:


LOL16MPG


/

[Mike689]

Originally Posted by jdlmodelt

I live in Colorado, 6200+ft elevation, I can typically only get 91 with ethanol. A station nearby recently started offering 91 without ethanol! Yay!. I get about 28.5 hiway with 91 ethanol and 30.5 with 91 non ethanol. I'd make sure your MAF sensor is clean. Of course fresh spark plugs don't hurt if its been a long time.

I'll look into the MAF sensor. I think my spark plugs should be ok, I just bought my car a few weeks ago with 78k miles. It passed the SMOG a couple months ago so it could be fine. I'll probably replace them next oil change.

[Mike689]

I refueled today around 3/4 tank. I had 61.0 miles on 4.142 gal which is a whopping 14.7 mpg. I had the tank filled with arco 91 and I used chevron today. I figure I'd make the change to chevron slowly. I also added injector cleaner yesterday so its only been a day with it.

I'm replacing the air and pollen filter on Friday, I'm hoping this helps. I'm also getting new rear tires tomorrow. Other than spark plugs and maf what else should I look in to?

[Gilles]

Arco…?

[BIGJake111]

I drive an S and get about 60 miles for each quarter of a tank myself. I usually fill up around 230 or so as this is usually near where the light comes on. The more highway driving I do the more these numbers creep up, the difference from city to highway seems massive on these cars, I'd say that your numbers are not that far off unless you are doing 50 mile round trips on the highway and getting these numbers.

[BH2000S]

Thanks for starting this thread. I'm also a Boxster S newby and have put about 1000 miles on my 2000 that has 54k on the ODO and 25k on the crate engine Porsche put in it. My computer was telling me over 21 MPG but that seemed high. I checked on the last tank and it was below 16 MPG (I also figured out how to reset the MPG on the computer and it is now reading about 15.8 MPG). Everything checks out, fresh oil change, correct tire pressure, clean K&N air filter. I do mostly city driving using crap Los Angeles 91 octane gas, mostly Shell. I did run a bottle of Techroline through the tank recently. I try to shift at higher RPM's but that usually puts me way over the speed limit and on the brakes so that I don't rear end someone. Going to keep watching MPG closely, maybe fresh plugs too. Car seems to run great.

[SC-986]

There seems to be a learning curve with these cars regarding engine rpm and shift points. When I purchased my 2002 base 4 yrs ago I averaged 17 mpg combined hwy/city. I am now averaging just over 21 mpg combined hwy/city.

More than any other car I've owned the 986 requires a period of time learning it's nuances before you can really experience it's performance capabilities.

I would reconsider your use of a K&N air filter. If too much oil is used it can end up on your MAF creating more problems.

[alm001]

Your method for sampling mileage is not very reliable. Different pumps will stop at different points, and with only putting in 4 gallons, a quarter gallon one side or the other could make a pretty big difference.

I track every tank, and fill when it gets low - usually before the warning. I try to use the same pump, but that's not always possible.

So far, with 5894 miles of ownership on my 2002 3.2
Average: 21.41mpg
Best tank: 24.08mpg
Worst tank: 17.71mpg

[Smallblock454]

OK, you really use 91 octane fuel? The ecu is designed to 98 octane fuel over here in Germany (fuel type is called Super Plus). Don't know if the US cars do have another ecu.

The fuel is to expensive? Well, over here in Germany 1 litre Super Plus is around 1,40 Euro at the moment. And that is a very low price compared to a year ago where we were at 1,80 Euro a litre. 1 gallon is 3,7854118 litre. So at the moment one gallon Super Plus would be 5,30 Euro, or 5,85 USD.

16 MPG = 16 miles per gallon

I have a Boxster S MT.
Fuel consumption:
Lowest was around 8 litre / 100 Km -> MPG = 29.40
Highest was around 16,5 litre / 100 Km (around 220 - 260 Km/h on the Autobahn all the time) -> MPG 14.25

The average fuel consumption of my car is at 10,5 litre / 100 Km which is 22.40 MPG

Bought the car new in 2003.

Regards from Germany
Markus

[RandallNeighbour]

97 base boxster 2.5 here and I get 27 mpg on the freeway cruising at 70 and get this, 8 mpg at the track during DE's.

Biggest gap I've ever seen in a car I've owned.

[alm001]

Originally Posted by Smallblock454

OK, you really use 91 octane fuel? The ecu is designed to 98 octane fuel over here in Germany (fuel type is called Super Plus). Don't know if the US cars do have another ecu.

The fuel is to expensive? Well, over here in Germany 1 litre Super Plus is around 1,40 Euro at the moment. And that is a very low price compared to a year ago where we were at 1,80 Euro a litre. 1 gallon is 3,7854118 litre. So at the moment one gallon Super Plus would be 5,30 Euro, or 5,85 USD.

16 MPG = 16 miles per gallon

I have a Boxster S MT.
Fuel consumption:
Lowest was around 8 litre / 100 Km -> MPG = 29.40
Highest was around 16,5 litre / 100 Km (around 220 - 260 Km/h on the Autobahn all the time) -> MPG 14.25

The average fuel consumption of my car is at 10,5 litre / 100 Km which is 22.40 MPG

Bought the car new in 2003.

Regards from Germany
Markus

Octane ratings are calculated differently here in the U.S.

91 octane in California would be 95 to you.

[jb92563]

For short 5 mile trips with a couple lights I think 16mpg is normal.

The first couple miles the engine is still warming up and throw in a couple lights and it just plain lukewarm city driving.

My drive in the morning is 15 miles, 6 miles with 16 lights city driving and 9 miles of highway at 70+mph.

I get 230 miles on 12 gallons(91octane) which is about 19mpg city/hwy.

My computer says about 16mpg in the city parts.

On pure Hwy cruising I have seen as high as 30mpg on the computer in 6th gear @75mph.

[Tailwind]

I "filled" my car for the first time and I stopped when it clicked off at 13 gal. Had 200mi on the trip readout, so 15.4 MPG This was mixed driving. Around town, I'm at or below speed limit, keeping the rev's around 2.4K. Next fill I will try to squeeze ~16 gallons in (I went onto reserve right after the dentist visit and drove about 25 miles).
I plan to clean my engine and do a TB/MAF clean. I have fresh plugs. I'm going to take the advice given here about shift points.

[Gilles]

Tailwind, out of curiosity, what is your tire pressure..?

[Tailwind]

Originally Posted by Gilles

Tailwind, out of curiosity, what is your tire pressure..?

29/36, as stated on the pressure label. Good thing I checked the spare. Apparently previous owner didn't; it had 2lbs in it. I aired it up to 60.