1980 911 Gas Mileage.....

[fred cook]

Does anyone know what Porsche claimed for gas mileage for a
1980 911SC? I'm currently getting about 18-19 mpg in town and 27-28 on the road. Completely stock engine except for an MSD ignition and aftermarket muffler.

Thanks!

Fred Cook
'80 911SC coupe


"You are never too old to have a happy childhood!"

[targa80]

WOW if you are getting that I would not complain. Last time I checked I was getting ~16 MPG city, 22~24 highway.

[nostatic]

13-15mpg city. Highway a few above that. Never seen 20mpg. Then again I tend to keep my revs up.

[jmohn]

I don't know what Porsche "claimed", but I'm getting 20-21 mpg combined (in reality more highway than city ... say 70:30); '78 SC, stock.

Jerry M
'78 SC

[fireant911]

Fred,
We are 'kinda' neighbors!!! Surely you posted this simply to brag... According to the Porsche 911 Buyer's Guide by Randy Leffingwell - "Porsche greatly improved fuel economy, by nearly 21 percent (to 29 miles per gallon highway/24 urban EPA rating) for the 1980 model year." Just out of curiosity, is your Oxygen sensor hooked up? I have been trying to find the cause of my 1981 SC poor mileage since I have owned this car. I religiously acheive 17.70 mpg for highway use. I have replaced my B&B stainless exhaust system with the factory unit and still my mileage is terrible. I have had my mechanic to connect the gas analyzer to properly adjust the Air/Fuel mixture to no avail...

[yelcab1]

if i get to 15 MPG combined, I'll be happy as a pig in mud.

[caliber60]

" I'm getting 20-21 mpg combined"

Me too.

[goliver]

My '79 SC gets 13-14 in town and 21 on the highway but I drive like I am trying to evade the police after a big heist. Highway it is hard to keep her below 90ish.

Cheers,

Geoff

[dotorg]

Lets just put it this way, in my '68, I get way better milage out of my 4.7l V8 in my Dakota.

I think I average around 13mpg in the 911.

[pauls81sc]

MPG Highway: Don't know, maybe 5% of my miles are highway.

MPG Around town: 12-13 (I've always wondered if this was considered normal)

[qcwang]

I have an 83 SC and on the original window sticker it says 16mpg but does not say if this is city or hwy. Hope this helps, maybe the 80 SC is similar?

[350HP930]

That's pretty good.

There have been times I have gotten as little as 10 MPG with the 930. It takes a lot of WOT though.

[fred cook]

Thanks, everyone. I was curious whether the mileage that I get from my SC was "normal" or not. When I first got the car about 3 years ago, the F.I. was set too rich and I was getting about 14 in town and 20 on the road. I bought a Gunson exhaust analyzer and set my fuel mixture so that the CO reads about 2% with the O2 sensor unplugged ( the way I normally run it). I don't baby the pcar, in fact my wife usually fusses at me for my "spirited" driving techniques. However, I do live in a very rural area with not much traffic.

Fred Cook
'80 911SC coupe

PS. FireAnt911...I've been to Jacksonville, Al several times. There is (or at least used to be) a small antique/book store on the south east side of the square. I bought a couple of the original 1910-1920 "Tom Swift" books from there. Isn't Jacksonville the home town for Troy State University? My son went to a couple of marching festivals there while he was in high school.

[singpilot]

I get 12-ish around town. 20-22 out on the highway, I do the Las Vegas- Los Angeles commute a lot. Mileage around town is better for a few days after the desert run. Yours sounds better than average. Everything on mine is stock, except no meow meow.

YMMV..... first time that has REALLY applied.

[speeder]

Originally posted by nostatic
Then again I tend to keep my revs up.

Me too. Usually about 4000+ in 5th gear on the highway.

I get ~13mpg in town, (and this is not WOT driving, just keeping up w/ L.A. traffic), and over 20mpg on highway. I would kill to get the mileage that you are getting, Fred, especially w/ the current price of fuel. Approximately what steady speed on highway are you seeing 28mpg.? Cruise control on in 5th @ 70mph w/ a 65mph tailwind?

[fred cook]

Speeder,

On the Interstate, I usually run between 70 - 80 mph. That is between 3000 - 3500 rpms in 5th gear. The cruise control on my car is not working so I can't give any numbers in that respect. All I have done to get this kind of fuel mileage is to make certain that the engine is tuned to the proper specs and run premium fuel. About a year or so ago, I was coming home from the Atlanta area one dark, moonless night and ran from Macon to Cordele (about 75 miles) at 100 or slightly better. I think the fuel mileage on that trip worked out to about 21-22 mpg. The MSD ignition system that I just installed seems to have improved my in town fuel mileage by about 1 - 1.5 mpg. I will have to run several more tanks to be certain.

Fred Cook
'80 911SC coupe

[350HP930]

Originally posted by speeder
I would kill to get the mileage that you are getting, Fred, especially w/ the current price of fuel.

Not counting the things you have no easy control over, A/F mix and timing will have a lot to do with your engine's efficiency. Other things are also important like having a healthy ignition system so you do not lose any power to misfires or incomplete combusion.

[wannaporsche]

I'm curious if anyone else finds these "in town" driving averages like 13-15 MPH city sounding a bit high. Driving my SC in Los Angeles stop and go traffic during the week, with a fresh top-end rebuild, I average about 10-12 MPG... but I've never gotten 13-15. I haven't taken it on a long highway haul, but I'm guessing from some coastal runs it would average in the low 20s.

(In fact I only get 15-17 in my 2.0 A4 in the same stop and go traffic...)

[Kevin911sc]

I guess I drive the old girl too hard? granted she has cams carbs a 1977 3.0 and low gears.... 10mpg reliably, and loving every second.

[timmy2]

My '78 went from about 15 combined to 18 combined with the Bitz EFI install, but I'm running it a little rich right now.
I hate ethanol gas and don't want to run at 14,7 AFR with it.


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