Catharpin

My .1 C4 with the Sport Design package struggles to get 24mpg on a 300 mi road trip averaging 68mph. Even with sport mode off it doesn't change much.
I see plenty of posts claiming high 20's, low 30's on the highway. Even my Corvette gets near 30 on the same trip.
Can I assume the ducktail and front splitter are to blame? Everything else seems normal, so that's about all I can come up with.
My overall and typical MPG is around 20. I am not complaining, I didn't buy this for the MPG. Just wondering if others get similar numbers with the body kit.

asellus

Tire compound, tire pressure, and weather conditions each individually will do a hell of a lot more to your MPGs than the splitter and duck tail combined.

Catharpin

Stock tires @ comfort setting. Traveled this route in June and November, same #s.

JW911

Seems impossibly low. Is the route hilly? Are you using cruise control?

asellus

I assume you mean that you put a new set of pzeroes?

Worth noting the .2 gets better mileage than the .1, and the PDK gets better mileage than the manual. The EPA tests show the .1 GTS at ~26MPG so you're not too far off. Could easily be fuel related. Could also be weight, was the car fully laden?

I wouldn't worry too much about it. I'd assume you're hearing those high 20s to low 30s remarks in regards to the 3 litre out of the .2.

AdamSanta85

Remember to enable coast mode in PDK by turning auto stop start on. I had to follow my buddy pulling trailer for a few hours on highway and was getting 30 in a PDK .1

BGLeduc

Another data point. The first week of October, I did a round trip from Albuquerque to Vero Beach, FLA. Outbound, 1900 miles, 28.7 MPG. The return, over a different route to avoid hurricane Delta, 1947 miles, 28.3 average. The numbers are from the trip computer within PCM.

‘15 GTS w/PDK. Two adults, as much luggage as I could fit. I never used sport mode or auto start/stop. We weren’t doing a Cannonball, but lets just say I enjoyed the performance the car has on offer.

Jack F

Enjoying the performance the car has to offer but not in sport mode? Hmmmm.......

BGLeduc

3800 miles of interstate cruising does not require Sport or Sport+.

Catharpin

Somewhat hilly, 81 through PA. from Harrisburg to NY border.

LexVan

Takes a lot of gas to cut through air at 81 mph. Even a slippery 911.

When were your engine air filters and plugs done?

Jack F

If you are saying that you are surprised at the mpg, then ok. If you are saying that you have data from previous trips that does not match up even closely, then the car is having issues. What year? Recent service? Mileage?

SoCal C2S

Consistently get about 22mpg with short weekend drives. But on longer consistent ~70-75mph stretches tops out just over 28mpg. Been like that since day 1.

asellus

Oh jeez I totally forgot about this concept.

In my experiences, car calculated MPGs are wildly inaccurate. Checking my logs here I peaked 27.3 mpg on tank with two 160 mile stretches. MFD said something like 31mpg. My G7R was the same way.

@Catharpin you're calculating your MPGs by fill and not just by the MFD readout, right?

Catharpin

Sorry, I-81, I averaged 68MPH, hit 130 uphill at one point. So I wasn't exactly trying to get good mileage. Car is recent on service, had 60K done earlier this year. I know the 911 in base form is pretty slippery but I wonder what effect the ducktail has. It must have more drag.

Car is 2014 M7 3.4, all up to date on maintenance. Mileage is consistent, asking since I see posts claiming a few MPG more.

Calculated from actual fill/odometer. The car display was a little higher, maybe 1.5MPG.

I don't think I have any problems, everything seems great. I do notice a difference in MPG when I have been using the car primarily for fun versus commuting. My wife thinks I am crazy that I actually record my expenses, but I like to know what things are costing me, and that I can identify an issue if my MPG drops, but it never has.
The body kit is the only thing I can think of to explain the difference, unless I really have an issue I am not aware of.