14mpg? what am I doing wrong (or right)?

[Bill Verburg]

Mileage has a lot to do w/ the engine management. W/ my original 3.0 liter CIS I got ~18mpg + or - . The larger 3.6 w/ DME gets closer to 30. Same roads, same driver, same routes, long term averages(on the order of 6mo)

[stlrj]

It might also be due to the torquey charaterisics of the 3.6 right down to 500 rpm range. It would be hard to expect much mpg on a 3.0 if you couldn't keep the rpms below 3000.

Joe

[nostatic]

well you *can* keep the revs below 3K on a 3.0....but why would you *want* to?

I'm not really complaining...I'm reaping what I sow, but I was curious about the higher mileage reports and wondering if I'm an outlyer or have issues. It would appear that the biggest issue is with my right foot.

[fred cook]

When I got my '80 911SC coupe 2 years ago, I was also getting about 14/23 for mileage. After buying an exhaust analyzer, I discovered that the CO was set waaaay too high (7% at idle).
I kept on leaning out the mixture until I got it down to 2% at idle. I now get about 18mpg in town and 25-27 on the road (steady cruise at about 75-80mph). The car runs just as strong as before, idles well and would meet the Georgia requirements for this year Porsche (2.2%, but not required in the south part of the state).

Good Luck!

Fred Cook

[nesslar]

I just got 24 MPG for two 88-mile round trips in my Carrera 3.2, and the drive includes maybe ten miles of varying 25-45 MPH travel, but mostly freeway at 60-64 mph. I hate citations; would love to cruise at xx+.....
I think I'll air up the tires a few PSI, maybe lean it just a touch, and check the MPG again, though it runs great as is, so why mess with that..... Fact is, I no longer have to get emissions checked, but the car always flew through that with great numbers anyway, not even close to a problem.
I would like to see 26+ out on the highway, and maybe slightly more air pressure would do the trick? I'm thinking I'll go with 32/36 PSI (my tires offer a great road ride, not for track or high speed); just added a quart of oil, too....
My car is pretty heavy (Targa), what with power sport seats, extra items in the trunk and interior too, heavy Cocos, stock trim, tail, not to mention a topped-up fuel tank for getting my MPG reading; probably I should be happy with 24?
I do get great mileage around town while still 'having fun'.

[redstrosekNic]

I've seen numbers below 12 for my 911, but I drive aggressively as my Porsches are my toys. I save the easy driving for my daily driver Like what was previously stated, keeping the revs above 3000 doesn't really help for mpg, but the earlier engines like it. I don't really care about my mileage in the Porsches, as they built for performance and fun, rather than economy.

[haycait911]

maybe I missed it, but what engine? my webered 3.0 hot rod occasionally gets 14. usually 10-12. sometimes under 10

[daepp]

I got an average of 18 in a 72 MFI over an 1100 mile trip. My son and I and a lot of gear. I think it's reliable as the mileage was from a Garmin GPS and the fuel was from modern digital meters.

[Milo2361]

Pre EFI conversion my 1980 SC was around 15-17 city, 20-24 highway, now its around 20 city, 27-28 ish highway... just started an SSI conversion so we'll see what happens when those are on.

[porsche930dude]

geeze the last time i clocked my 82 it was like 17 /28. same as the factory says

[tuchan]

81sc Running 98 octane here in Oz, highway 60-80 Mph she gets around 22 Mpg. With some needed tuning this will improve.

[rnln]

I have read people get up to 30+ too. I have tried several tanks of 99% freeway, shift at 3k RPM. I could get it up to 22k or 23k max. If I have fun, I have to fill up a lot sooner.

Originally Posted by nostatic

ok...these posts about people getting over 20mpg. My last tank calculated out to just under 14mpg. The car runs fine, but is this low? I will admit that I typically don't shift until 4K minimum, and prefer to be up around 5K. I also end up cruising at over 3K...I rarely see 5th gear, and sometimes not even 4th.

For those getting good mileage, are you hanging around 2K most of the time? If so, how do you pull that off? My car doesn't seem happy unless she's above 3K. Just curious...

[uncle_scott]

I average about 350 miles to my tank, and it seems 18 gallons is about my average fill-up. About 20 mpg in mixed driving, stop and go as well as freeway. I wouldn't expect to get much more than that. For a car that makes me smile every morning, I think it is well worth the cost .

[pete3799]

Got 24mpg on a trip to Boston and back last year.

[Scott Douglas]

My last fill up I got 18.
That torque multiplying torque converter makes it so much fun I can short shift it all day long and still enjoy it.

[Bob Kontak]

Originally Posted by pete3799

Got 24mpg on a trip to Boston and back last year.

I drove my US 81 at 65mph on a trip and got 27mpg. Drove it like a little girl. Then found out the speedometer (like most of them) is too fast. I was going about 59mph which is close to the EPA speed for mileage estimates.

When I drive (GPS) 75-80mph I get 23.

[sennasixty8]

The original 2003 fuel prices posted in this thread are nostalgic..

[stlrj]

Not to worry. At the rate fuel prices are increasing, all our thirsty 911's will soon be memories of a bygone era, gathering dust in some obscure Nevada museum.

It's only a matter of time...