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Discussion Starter · #1 ·
One of the things I love about my 981 is how great it is as a long distance tourer -- fun to drive but also very comfortable.

A pleasant surprise to me was the fuel economy you can get from a high-performance naturally aspirated engine. I'm no hyper-miler but this past weekend I took some twisty hilly back roads that were relatively slow in the speed limit department and was shocked when I checked the trip's fuel consumption. 7.1 l/100km (33 mpg US).

Font Text Auto part Speedometer Photography


The next time I filled up I checked the computer against the actual mileage on the tank and it is very accurate.

What's your best or worst fuel economy numbers? I'm sure there are some folks out there with track day numbers that are entirely different. Post pictures if you have them.
 

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The computer bottoms out at 8mpg on the track although it is worse than that. I'm curious if anyone has actually calculated true track mpg. I don't fill at the pump so i dont really know... I estimate the approx amount to add without overfilling with my flofast pump.

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I am curious as to what engine you have - the 2.7 or the 3.4? I have only seen mileage like that on straight highway cruising with my S. On my usual jaunts up to the highlands that you are familiar with, I usually wind up around 10 L/100 km, and my average speed is not that much higher than yours. I do cane it pretty hard in the fun stretches - it's always in Sport mode and I wind it out when I can.
 

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My 981 BS can average around 28 mpg on the highway doing 70 mph, but typically I average around 20 mpg doing my 25 mile round-trip commute with spirited driving.

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I'm also not seeing anywhere near that kind of mileage with the 3.4. I get perhaps 28 mpg (US) on a long distance cruise on the highway. Daily driving in Bay Area traffic I get 17-20 mpg. For twisty back roads, forget it!

The 2.7 I rented before buying into the platform got the kind of mileage the OP is talking about. The gas meter on those would sit around 450-500 miles to go for freeway driving on a full tank. Mine shows about 350, maybe 375 under the same conditions.

I also get a lot of soot on my exhaust tips. Has to be cleaned off every time I wash the car (1-2 weeks).
 

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Round trip to Orlando airport, yesterday (260 miles), I showed 33.9 mpg on the computer as I pulled off I95 exit for home. This was averaging 70-75 mph most of the way. This was running in rain for about half the return trip with lights, wipers, and AC on.............not the first time I have seen this type of mileage. I saw some similar mileage in my 2014 too. 2.7L, PDK 19" PZeros, X73 running air at 30 front 32 rear.
 

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Discussion Starter · #7 ·
I am curious as to what engine you have - the 2.7 or the 3.4?
I have a Cayman GTS, so the 3.4. You can see that I managed to average 90kph over the drive so I wasn't holding back on what was mostly 80kph roads. But I started out early in the morning and the temp was perfect (AC not needed but warm enough for an efficient warm-up process).

It may have something to do with my oil now that I think about it. I'm running Mobil-1 5w-50 (which is an approved weight).

Transmission is 6M.
 

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I've never paid much attention to the trip computer, but running down to an appointment last week 80 miles away on mostly county/state roads (no pure highway), I noticed I was having supernatural luck with the occasional traffic lights. I was most of the way there w/o stopping for a single red light, so I checked the computer and it was over 30mpg. When I got there it was at 32.0mpg. It had turned into a game by then, but on the return trip I started hitting all those lights I missed on the way down. I turned on the start/stop feature, and that plus the coasting feature allowed me to get home at 32.1mpg for 160 miles. I didn't really try any blatant mileage tricks. I drove using the CC set 7mph over the sped limit as much as traffic would allow.

Can't say it was all that much fun driving that way, but I was pretty curious to see how it would end up. Now that I know, I can pretty much guarantee it won't happen again. Emoticon Yellow Black Smiley Smile
 

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My '15 BGTS with a PDK, on the open highway averaging 70-75 mph, will get 32-34 mpg. I too was amazed in the beginning and thought it was an anomaly, but over the past two years those numbers have been consistent. Pretty impressive for a 3.4 l. sports car that will crank out 330 HP!
 

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Discussion Starter · #10 ·
My '15 BGTS with a PDK, on the open highway averaging 70-75 mph, will get 32-34 mpg. I too was amazed in the beginning and thought it was an anomaly, but over the past two years those numbers have been consistent. Pretty impressive for a 3.4 l. sports car that will crank out 330 HP!
I was wondering if the top would have a detrimental effect on mileage, but clearly your experience indicates that it doesn't.

My last NA sports car engine was a VR6 2.8L and on average the mileage was about the same as the 981. 20 years later and you get twice the HP with the same fuel economy. It's amazing!
 

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I'm also not seeing anywhere near that kind of mileage with the 3.4. I get perhaps 28 mpg (US) on a long distance cruise on the highway. Daily driving in Bay Area traffic I get 17-20 mpg. For twisty back roads, forget it!

The 2.7 I rented before buying into the platform got the kind of mileage the OP is talking about. The gas meter on those would sit around 450-500 miles to go for freeway driving on a full tank. Mine shows about 350, maybe 375 under the same conditions.

I also get a lot of soot on my exhaust tips. Has to be cleaned off every time I wash the car (1-2 weeks).
My ride: 2015 CGTS with PDK. in Sport mode, I generally get that 28 mpg for cruising... but with Sport mode turned off, e.g. "non-sport-y" but with auto-stop disabled, cruising I routinely get 30-31+ mpg, as when I come to the bay area from my "perch" up in the foothills (so, most of the trip is not in that nasty traffic you talk about. interestingly, on the same sort of trips with my first Cayman (an '07 2.7L), I would dearly get up to 30. I think the PDK's 7th gear and the more torquey 3.4 makes up for the increase in displacement.. Just my 2 cents.
D
 

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My ride: 2015 CGTS with PDK. in Sport mode, I generally get that 28 mpg for cruising... but with Sport mode turned off, e.g. "non-sport-y" but with auto-stop disabled, cruising I routinely get 30-31+ mpg, as when I come to the bay area from my "perch" up in the foothills (so, most of the trip is not in that nasty traffic you talk about. interestingly, on the same sort of trips with my first Cayman (an '07 2.7L), I would dearly get up to 30. I think the PDK's 7th gear and the more torquey 3.4 makes up for the increase in displacement.. Just my 2 cents.
D
I'm on 6MT, sport mode off for my example figures That extra tall gear with the PDK might be making the difference. Not really worried about it. I've accepted the fact that my CS slurps fuel compared to the 128i I was driving previously. Completely different animal, and 28 really is not bad. The computer will show 30+ if I drive economically on smooth highway, but final numbers never work out that way once you add the town driving required.

Which foothills is your perch in? I live at the base of the hills near where alum rock splits to highway 130.
 

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The computer bottoms out at 8mpg on the track although it is worse than that. I'm curious if anyone has actually calculated true track mpg. I don't fill at the pump so i dont really know... I estimate the approx amount to add without overfilling with my flofast pump.

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I've seen 16L/100km with the 3.2 Boxster,on the track, and as low as 25L/100km with the 981CS, which was also 10sec/lap faster!

In the real world 7 to 8L/100km is common.


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Around town (Columbia/Nashville) the trips are usually about 10-20 miles. Mid 20s is typical for what I see.
My commute from Columbia to Huntsville, AL is usually 28-31 depending on how spirited I am and how much I play with the 'coast' feature on the PDK.
Saw similar on trips to Knoxville and Gulfport MS. Even in Sport mode on long haul trips, we are talking 27+ MPG without effort.

I find my GTS cruises the most comfortable (and efficient) at around 85 mph. 70 is not optimal.
 

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What do you mean by efficient? Are you saying you get better mpg at 85mph than you do at 70mph? How do you burn less gas at higher rpms? That is a trick I'd like to learn.
Speed is a factor in the mileage equation. That's why we don't get the best mileage crawling in traffic at idle. But I am surprised that he's seeing improvements at 85 vs. 70 mph. We would need tabulated data with multiple samples to really find out though. This is all rough guesswork so far.

(Edit: I really hope no one goes there... These are not hybrids afterall...)
 
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