What mileage do you get from your 32v 928's?
07-10-2009, 12:41 PM
#16
Hmm. I may have an issue.
I get 15-16 around town and never get over 20 on longer trips.
Of course I occasionally "hit it", but probably no more than any other 928 driver.
My car feels like its is running well, but I wonder if I have a subtle issue?
'88 Auto
-Ken
I get 15-16 around town and never get over 20 on longer trips.
Of course I occasionally "hit it", but probably no more than any other 928 driver.
My car feels like its is running well, but I wonder if I have a subtle issue?
'88 Auto
-Ken
07-10-2009, 01:36 PM
#18
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I have said this before, but perhaps it bears repeating...
On the LH cars, you can noticeably improve your mileage with a slight change in driving habits. When you lift your foot totally off the throttle while coasting at above about 1500 RPM, the LH completely cuts off fuel injection. If you hold the throttle down just a tiny bit (so that the idle switch is open), you still get injection. This means that with injection cut off, you are getting infinite mileage (the car will tell you 90 mpg, but it lies), while with just a tiny bit of throttle you are getting about 50 - 60 mpg.
In gently rolling hills, the difference on my '90GT (not one of Porsche's economy models) is 19-20 mpg driving "normally" and 21-23 lifting off completely at every opportunity.
While it makes no difference in average speed, trying to do it will drive you nuts...
On the LH cars, you can noticeably improve your mileage with a slight change in driving habits. When you lift your foot totally off the throttle while coasting at above about 1500 RPM, the LH completely cuts off fuel injection. If you hold the throttle down just a tiny bit (so that the idle switch is open), you still get injection. This means that with injection cut off, you are getting infinite mileage (the car will tell you 90 mpg, but it lies), while with just a tiny bit of throttle you are getting about 50 - 60 mpg.
In gently rolling hills, the difference on my '90GT (not one of Porsche's economy models) is 19-20 mpg driving "normally" and 21-23 lifting off completely at every opportunity.
While it makes no difference in average speed, trying to do it will drive you nuts...
07-10-2009, 02:17 PM
#19
O2 Sensor is new, less that 500 miles on it. Switched it when I last checked thrust bearing, ( because thats when I dropped exhaust, giving easy access to sensor as well as measuring TB pressure and play...).
Latest tank average was 15.2 of mainly commuting, with a few spirited romps. No long drives.
Since mine is an '88, measurement is based on the "tripometer miles /fillup gallons" method, not on any digital dash readouts, and I can't accurately measure milage on short trips.
Wally has a good point, driving style is critical. While I don't _think_ I drive any more aggressively than others, its just darned hard not to drive with a little spirit in a 928...
-Ken
Latest tank average was 15.2 of mainly commuting, with a few spirited romps. No long drives.
Since mine is an '88, measurement is based on the "tripometer miles /fillup gallons" method, not on any digital dash readouts, and I can't accurately measure milage on short trips.
Wally has a good point, driving style is critical. While I don't _think_ I drive any more aggressively than others, its just darned hard not to drive with a little spirit in a 928...
-Ken
07-10-2009, 02:41 PM
#20
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I get about 18 - 20 tank fills per set of rear tires. I don't bother keeping track of MPG.
My tire man just laughed when I asked him about a mileage guarantee. He rode in the car once
Last edited by Sailmed; 07-10-2009 at 03:04 PM.
07-10-2009, 04:06 PM
#22
Rennlist Member
FWIW Ken, do you row 3-to-D around town? There is a sweet spot with manually shifting the AT, such that you balance throttle/speed/gear.
Remember, in D above ~35mph constant speed, you'll get 4th-OD. If you intend to accelerate a little, you'll actually require more fueling to lug out of 4th than you would if in 3rd. It is surprising how much this occurs in normal city driving and really kills the mpg if you drive >50% in the city.
Leaving it in 3rd when appropriate to keep the engine above 1200rpm lug mode or pulling D-to-3 for slight acceleration will help a great deal. You'll get the feel for the sweetspot rather quickly if you try it. Same goes for 2nd in traffic as well, but many don't care for the "start in 3rd until moving, then pull down to 2" process. Either way you'll find the range for best economy with each gear fairly quickly, once you start.
Oh, and same goes for uphill on the fwy - constant 65ish up a grade will usually require less throttle if you pull to 3rd than if you stay in 4th-D.
Good luck!
Remember, in D above ~35mph constant speed, you'll get 4th-OD. If you intend to accelerate a little, you'll actually require more fueling to lug out of 4th than you would if in 3rd. It is surprising how much this occurs in normal city driving and really kills the mpg if you drive >50% in the city.
Leaving it in 3rd when appropriate to keep the engine above 1200rpm lug mode or pulling D-to-3 for slight acceleration will help a great deal. You'll get the feel for the sweetspot rather quickly if you try it. Same goes for 2nd in traffic as well, but many don't care for the "start in 3rd until moving, then pull down to 2" process. Either way you'll find the range for best economy with each gear fairly quickly, once you start.
Oh, and same goes for uphill on the fwy - constant 65ish up a grade will usually require less throttle if you pull to 3rd than if you stay in 4th-D.
Good luck!
07-10-2009, 04:26 PM
#23
My driving style varies, sometimes rowing, sometimes letting the AT do all the thinking.
I'm not really concerned about the actual MPG as such, and not trying to milk every last mile out of a fill up.
What concerns me is that, if I am , on average, driving my 928 like most other people do and I am getting worse milage, I may have a hidden issue.
Complicating it is that driving style is very subjective and also has a big impact on MPG, so what I consider "average" may be agressive.
Real problem is that I may become a "shark hypocondriac": Just because a few people report better milage than me, I see issues where there may not be issues. I can certainly find enough to do on my car without going on a snipe hunt based on vague and unreliable symptoms....
-Ken
I'm not really concerned about the actual MPG as such, and not trying to milk every last mile out of a fill up.
What concerns me is that, if I am , on average, driving my 928 like most other people do and I am getting worse milage, I may have a hidden issue.
Complicating it is that driving style is very subjective and also has a big impact on MPG, so what I consider "average" may be agressive.
Real problem is that I may become a "shark hypocondriac": Just because a few people report better milage than me, I see issues where there may not be issues. I can certainly find enough to do on my car without going on a snipe hunt based on vague and unreliable symptoms....
-Ken
07-10-2009, 05:23 PM
#24
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They'll forget your name, and won't remember to write up a bill.
Just be careful not to run over their tongues when you back the car out of the stall.
07-10-2009, 05:35 PM
#25
Rennlist Member
On the way to SITM, with my 87 5speed twinscrew, we got a little over 22 at 75-85, on the way back behind a speeding SUV from Knoxville to Louisville at 80-90, the rest at 75-80, I got a little over 21.
When I picked up the 87 5speed, red one in Toledo (off the tranpsort truck) and drove it back to Muncie, I got 27mpg, but that was strictly speed limit, since my police friend was following me in my truck.
I was very happy about both of those.
Rod
When I picked up the 87 5speed, red one in Toledo (off the tranpsort truck) and drove it back to Muncie, I got 27mpg, but that was strictly speed limit, since my police friend was following me in my truck.
I was very happy about both of those.
Rod
Last edited by Rod Underwood; 07-10-2009 at 06:26 PM.
