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

986sport · 07-10-2007, 05:04 AM

I just bought an 03 Boxster with 18" wheels. I put all-season tires on it. 5 speed.

On my first trip to the mountains in Eastern PA, I got 35 mpg going up and 36.5 mpg return. That's mostly highway top up, top down/windows up on the side roads, some AC on returning, highway speeds to 75, mostly 55-65.
Around town, short trip suburban driving, I'm getting 26-27 mpg. I use 92 & 93 octane gas.

The car is EPA rated at 20/29 mpg. I seem to be doing much better, especially on the highway--so the numbers look to be very conservative.

Any other experiences out there? I'm surprised at these numbers, which I verified in several fillups.

Spy4cia · 07-10-2007, 07:41 AM

Running AC all the time, top up, average speed 75 mph...

I was pretty happy...

dmenn · 07-10-2007, 07:55 AM

Those numbers seem on the high side, however in this case that's a good thing.

Are you calculating the MPG based on miles driven/gas filled up, or is this the number you're reading off the OBC?

rick3000 · 07-10-2007, 09:16 AM

I recently returned from a 750 mile one way roadtrip. So I put 1600 miles on the car total. I averaged around 20-24 around town doing mostly 40mph and some bumper to bumper. On the freeway doing 80mph I got up to 32mpg but the average was around 29mpg. I was even shocked when the OBC told me I had a 500 mile range until I started driving and it dropped to 450 mile range. So it was right around the EPA milage with the air on medium the entire time, and in a 2.5L.

Did you mod anything on the car, I would love to get that kind of milage? Or are your numbers possibly wrong, did you calculate from range or with the OBC?

BoxsterBob - CA · 07-10-2007, 02:35 PM

Quote:

Originally Posted by rick3000

I recently returned from a 750 mile one way roadtrip. So I put 1600 miles on the car total. I averaged around 20-24 around town doing mostly 40mph and some bumper to bumper. On the freeway doing 80mph I got up to 32mpg but the average was around 29mpg. I was even shocked when the OBC told me I had a 500 mile range until I started driving and it dropped to 450 mile range. So it was right around the EPA milage with the air on medium the entire time, and in a 2.5L.

Did you mod anything on the car, I would love to get that kind of milage? Or are your numbers possibly wrong, did you calculate from range or with the OBC?

Wow. 32 MPG? The best I ever did in my '99 Ocean Blue Boxster (you have great taste in cars, BTW) was 27 MPG coming home from Lake Tahoe, all down hill. I typically get 20 mpg with 70/30 Highway/City

pteam · 07-10-2007, 02:46 PM

They say a K&N air filter increases gas economy 5%. Even more if your replacing a pretty dirty filter then going to the K&N. 5% = 1mpg on a 20mpg avg. Who knows if its really true or maybe its really 2% or up to 5% but some is better than none, and its much better than a dirty filter.

Does the boxster S get less gas milage than a Non S?

986sport · 07-10-2007, 10:04 AM

Quote:

Originally Posted by dmenn

Those numbers seem on the high side, however in this case that's a good thing.

Are you calculating the MPG based on miles driven/gas filled up, or is this the number you're reading off the OBC?

I'm reading the miles driven since last fillup off the on-board computer, and the gallons on fillup. The on-board mpg indicator which measures avg mpg since the last fillup agrees with the total miles driven/gallons pumped. I set the miles back to zero after each fillup.

OldBlevins · 07-10-2007, 10:18 AM

I just got back from a 2500 mile road trip between Seattle and central California, and pretty uniformly got 26 mpg. It didn't seem to matter whether we were on curvy mountain roads or the straight-shot of I-5, or if we had the a/c compressor on or off. With a 3.2, I was pretty happy with that mileage.

FrayAdjacent · 07-10-2007, 10:38 AM

Driving from Austin, TX to Phoenix AZ... a little local driving, then back to Austin... I averaged 31mpg. I was quite impressed.

This was mostly on I10 at ~80mph both ways.

986sport · 07-10-2007, 01:39 PM

Quote:

Originally Posted by 986sport

I'm reading the miles driven since last fillup off the on-board computer, and the gallons on fillup. The on-board mpg indicator which measures avg mpg since the last fillup agrees with the total miles driven/gallons pumped. I set the miles back to zero after each fillup.

miles driven on odometer/gas filled up.

agrees with the mpg on the computer.

wonder what I can do on cruise control. maybe 40 mpg.