Irfan

Got my .1 in June with 18,800 miles, one owner and plugs were done last Sep at 18,400 miles. Prior to it was done at 15,600 miles in Aug of 2021. It was a Minnesota car from new (91 Octane), but it's crazy that I am getting 10-12MPG in S+, not even pushing her hard. Is it normal? I am in FL, she is drinking 93 octane.

MPawelek

Are you doing your regular street driving in S+?

DC911S

I'm guessing your running the AC the whole time as well. I've found that here in the mid-Atlantic when I'm in S+ with AC on and driving it a bit hard at 90+.....she swallows the gas pretty quickly.

shammerman

If the PDK has been reprogrammed (emissions gate) it works out fine in street driving and is phenomenal in spirited back roads carving. No more only redline upshifts - only if pushed with pedal to the metal - otherwise upshifting at about 3,800 rpm.

Irfan

Mainly around town with no traffic.

mwjackson92

10mpg is pretty low. I was averaging 21mpg for the first 18 months I owned my car, but when I had PSE and Sport Chrono Package retrofitted I slipped down to 14mpg average. So definitely sucks down gas much more listening to that glorious note!

Irfan

Yes, got all that turned on, plus AC in FL heat.

Pavegeno928

2014 991.S with power kit (50th Anniversary) Manual Transmission, sport chrono, PSE
No mods
a/c always on in SE Albama
106K miles
All regular/scheduled maintenance

City driving - 25 mpg - Sport Plus on
Highway driving - 31 mpg - normal mode

In Germany on Autobahn at 150 mph+ or running very, very hard in the mountain roads, worst I ever saw was 15 mpg.

Something is very wrong.

Irfan

Maybe it’s the gas, I am thinking. Drives fine. Always was serviced at Porsche, plus had PPI done as well. I will fill up at shell next few times, will report back. I was getting 15-18MPG when I bought it, but haven’t really looked it unlit yesterday.

Pavegeno928

Make sure you are using 93 from a name brand. I run a fuel treatment such as Techron or Seafoam every 3000-5000 miles. You might do one of these each refill a few times just to see if something is fouled up. Anything obvious like fuel smells from a leak or any odd smells from the exhaust? If you have an icarsoft or other diagnostic tool (even an auto zone shop will pull them normally), check the codes and perhaps there is something there. When the plugs were done, were the coil packs looked at/replaced?

If you bought it from a Porsche dealer make sure they did the two recalls on the 991.1. The first was a Heat Shield for the engine. The second is for a Fuel Tank Leakage Module. Below is a picture of the work order performed by a Porsche dealer for free.

Here’s a generic checklist: https://mechanicbase.com/driving/cau...r-gas-mileage/

Good Luck!

Irfan

Thanks! Don’t see any recalls. I will call the dealership in Minnesota to see if that was taken care of. Also plugs and filter are new. What jumped out right away from the article is wheel alignment. Prior to my last fill up, just installed 15mm rear and 12mm front spacers. I think most likely the cause of the bad MPG. I will have to get the alignment checked.

bkrantz

What do the inside of your tail pipes look and feel like? Super-rich tuning would suck fuel and leave your pipes very sooty.

Irfan

Normal black residue.

Pavegeno928

Let us know what you find out! Good luck. Love the 991.1!

Bud Taylor

I drive in a spirited manner in Florida and S+ is always on...2012. The lowest Ive ever gotten is 18 to 20 and 30 on highway at 83mph is normal. MT on mine though perhaps pdk issue ?