BenCD

I am up here in VT, hilly country, 35-55 mph, no traffic, single lane-one lane each way-roads. I had averaged about 35-40 mph and 33-35 mpg overall average.

I have seen many mention that they get over the 29 mpg hwy but as I strive for at least 75 mph-hey, I have places to be and no traffic, I'm not wasting time trying to eek out every mpg, so while I get right around 29 mpg, I don't get much over unless I'm taking it really easy. Even though it is winter, it also happened to be a mild day that was at least in the mid 30's if not low 40's and I have had the "fix" done.

I've always noticed that anytime I need to do 30-50 on roads with no traffic, the mpg goes way up and over 30 mpg, which does make me happy.

I'm also happy that towing my snowbike only on the trailer still gets me about 21 mpg while averaging 65-75 mph on the highway. I'm one that has found no problem or issue with the fix.

GrandPaJohn

I've found that 65-70mph is the falling off point for good mpg numbers. If I keep it under that I'm seeing 35-37mpg. Over that and it starts dropping down to the low 30's. Not sure I can believe that, but that's what it says.

wkearney99

Yep, with any vehicle, the faster you go beyond 55mph the more your fuel consumption is going to increase.

However, I'm definitely not that patient, nor frugal.

desmotesta

I am slightly envious of the Diesel Cayennes. I get 15-16 MPG if I am lucky around town and MAY BE 20-21 on long trips on my '13 GTS

I wonder if it is possible to get a diesel with PASM and PDCC/PTV, get a tune for higher boost and the diesel may be the best all rounder in the line up.

sclemmons

This was on I 40 from Memphis, not hyper-miling, just keeping up with traffic.

r553

After the fix I see 36 MPG at 60 mph computed while the display shows 39 MPG

GrandPaJohn

Was it more accurate before the fix?

Falcondrivr

r553

No. The car has always been reading about 3 MPG higher than hand calculated. The fix seems to have reduced my highway MPG by 3 MPG.

skiahh

I know there's a wind resistance/drag increase at high speeds, but I wonder if there's a break point between distance covered and fuel consumed vs speed. As strange as it seems, driving at 45ish seems to get a bit lower mileage than a steady 60.

On a recent trip to Seattle, I reset the trip odo getting on the highway and by the time I got to my destination (including about 5 miles through town in Seattle), the mpg display showed 33.6. Can't remember what the average speed was, but for a good portion of the drive, I was going with the flow at 75-80ish. Same numbers on the return trip. That was in the '15. Repeated the trip in the '14 a couple of days later, and it was 32.something, but I didn't reset it getting on the highway, so had some around town on both ends. Same speeds.

Tuning it may make it behave more like a GTS... but will also make it burn fuel like a GTS. Maybe not as bad, but you won't see 30+ if you're pumping out more power. Most of the tuning boxes I know of for my Cummins offer an efficiency setting that restricts power but kicks up mpgs. Good for unloaded highway (flat, that is) cruising, but not much else. But switch up the power on those boxes and, well... just don't mind the fuel gauge.

BenCD

I forgot to mention, up in my neck of the woods, it is always hilly and somewhat mountainous,but I have been finding that the 30-50 mph range gets incredible mileage provided there is no traffic.

projekt-h

Diesel + Tune = possibly the best combination for a daily ever, in most any form.

I just wish diesels were at all available near me, and the few that ever popped up weren't ridiculously expensive, Though I really have no complaints in regards to the mileage of my '11 S. Usual was 21 average. All highway 23-ish, and doing country roads and the speed limit (70) on the freeway coming back from my usual biking trails I got just over 25mpg.

desmotesta

wow

they must have installed Lead weights on my GTS.. cant break 16-17 MPG in city.. and thats with me trying very hard to not get on the gas..

merbesfield

wkearney99

Slower, when? Off the line from a dead stop, while rolling in stop/go traffic, at highway speeds to pass?