How exactly did you figure 34 mpg? Did you take the miles driven and divide by the number of gallons it took to fill the tank back up to full (assuming you started with a full tank)?

Only checked it carefully one time. 1300 mile trip that was 95% Interstate and averaged about 65mph. Used GPS for mileage. 25.5 MPG. Totally stock 88 Carrera Cab with fresh oil and recent major service.

You do have to start with a full tank and refill the tank at the end of the trip to get any kind of accuracy. Fuel gauges are VERY approximate.

+1. I'm averaging almost 18 MPG in city cycles.

While still jacking around with my jetting I'm getting around 17. However, I've noticed that there is a discrepancy between my GPS and speedo of about 3mph. I think if I do the next tank with GPS tracking I'll find it's a bit better.

I also hope it will improve when the jetting is perfect. I'd be happy with 25. We shall see.

-Dan

What is the RPM range for the best fuel saving? 2k-3k ?

While many people think this, in general it's not true. Modern cars run "closed loop" under normal driving conditions (not full throttle). Since the car is running closed loop, the computer is supplying fuel to run a perfect mixture (stoichiometric). If your filter is dirty you will get less air at a given throttle position but the computer will supply less fuel so the mixture is the same and the mileage is the same.

-Andy

While you are correct, it would make sense for fuel consumption to rise, ceteris paribus, with the return of a factory air box or filter. While the fuel injection delivers less fuel to go with the smaller amount of air, the engine will have to work harder to achieve the same acceleration that it did with a more breathable air box and filter. Because the engine needs to work harder, it will use more fuel. It can be compared to an air compressor using less power when it is fed 240 volts, as opposed to 120. The compressor isn't stressing the power supply as much when there is more to spare.

My owner's manual says that the fuel mileage my '87 ROW Carrera shout get is 7.9 km/100 litres. This is equivalent to 29.7 US MPG. Mind you this is in just about perfect conditions, I would suspect.

The best fuel mileage I have ever gotten in my '87 is just over 29 US MPG. This was a 200 mile stretch of highway through the mountains from about 3800 feet to just above sea level. My speed ranged from about 60 - 85 MPH with an often heavy foot.

I keep a spreadsheet of fuel fill ups and mileage. This measurement is consistent with previous fills, with similar usage, though somewhat higher this time.

On a bit different note, a few months ago, I almost ran out of gas with some surging and sputtering rolling up to the pumps. With about a quarter tank since my last fill being used running around the city, I managed to drive almost 600 miles (964 km) if you take the odometer as being mostly correct. If one assumes the pumps as being accurate, I put in 86.8 litres of gas. In an 85 litre tank. I'm not sure how that works...

My 911 got 26mph towing a small trailer......34 is doable with mild driving.

Paul Frere notes a record low for consumption with the 3.2L at 187g/hp/hour at 2,600 rpm.

I assume 5th gear on a level, at sea level, low weight, at 2,600 rpm with a new engine would be the max mpg...about 100kph with a euro car and G50.00.

Frere 5th ed

bingo!!!

90% surface streets with plenty of stoplights, heavy right foot, frequent A/C use=17 mpg.

Once it cools off, I'd expect to see a 1-2 mpg improvement.

I purchased my first 911sc in July, 2011. Drove it 473mi back home in Illinois. I got 27 mpg. I was very happy with this kind of mileage since I acquired the car without a PPI. It has 84,500 mi on the odometer.

:)

On a trip up North in a 86 911 last week I decided to use the GPS.

I was surprised to see about a 10mph difference between the 85 mph indicated on the speedo and the 75 mph showing on the Garmin.

Thats more than 11% error in speed and in total miles traveled.

More than enough to throw a fuel mileage calculation off by a lot.

Too bad the Garmin doesn't show total miles driven.

Len

:)

Just got back from a round trip to Beverly Ma. to get my daughter from college.
Filled up when i left.....refilled at same station.
326.5 miles /13.366 gal. = 24.43 MPG
Mostly 68-70 MPH till i got near Boston then had to go 75 to stay with the flow of traffic.:rolleyes:
Quite windy today....probably could have done better without the wind.

There are 2 real ways to check your Fuel Mileage and what the Gauge shows will never be one of them!

ALL will start with you either Filling the tank to either the CLick of you see the Fuel at the top. EIther way you must do this the same way when refilling.

You can either set the GPS of Trip Odemeter to 000 and start the trip. WHen time to fill up again, at the above person noted above write down the Number of gallons (Including the tenths) and divide the number of miles (Either the Odometer or the GPS) by the Number Gallons of Fuel and "THEN" you will know the answer.

My 1976 2.7 on NON Ethanol gasoline got between 27 to 29 MPG depending on how much I was enjoying the car. Our 1982 3.2 with Ethanol (Read 10% Ethanol causes 10% LESS MPG) gets 25 to 27 MPG on the road.

SO my answer is also NO you did not get 34 MPG!

3200 RPM hwy cruising my 82 sc will get 32 mpg as verified by gps. Just lucky I guess?

If a 76 2.7 could get 29mpg under normal conditions, I'd think a 74 with less emissions could possibly get 34mpg with a tailwind and moving downmountain at a somewhat higher than sea level elevation.

I'm thinking Mike that you're calculating an IMPERIAL gallon, no? My 85 will, on occasion, get that (32mpg)....in Imperial gallons but definitely not in US gallons. Cheers

:)

For calculating fuel mileage, you must know the miles covered with a full tank of gas.

I would think using a GPS is the most accurate way of measuring total distance traveled.

My Garmin shows the rate of speed in mph, but how do I determine the distance driven?

Of course, I never read the instructions, just plugged it in.

Len