This entire winter season I've been getting 180-200 miles to the tank with usually city driving, which equals about 12-13 mpg. I changed the t-stat because the engine was running cold and now that's more so normal (she runs at about the 1 heavy dashed line, that's about normal right?), and my mileage is still about 12-13 mpg. What else can I check to see what is causing this? I don't recall last winter being this pathetic on the fill-ups.

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Tune up time, possibly. How many miles on the car? Plugs, maybe wires, what temp thermostat did you put in?

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One Big Ass Mistake America

New plugs, wires and coolant were done a few months ago, i believe it is a 180 t-stat. Could it possibly be a fuel filter? When my friend tried to swap it out it was rusted and would not budge.

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I have the same problem with my fuel filter.. car runs great, just figured I'd change it but I can't get it off so I haven't bothered.. Alignment? Sticky caliper?

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My dad suggested the sticky calibers as well. I''ll driver her around the block and test that out.

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A couple things to think about. Does your car fun for a while to warm up each day. It is winter and my mpg goes down at this time of year. Is there more stop and go traffic and hills where you live. May be give you car a scan and see what is going on.

What kind of plugs did you put in? I would def change the fuel filter. just use some PB Blaster on the bolts, works like a charm. And i would assume you checked the air filter and tire pressure? you know...the easy things?

also, i would assume you run 93 Octane in your car since its a GTP?

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2000 Grand Prix GTX (32K) sold Oct 2009
1998 Grand Prix GT (102K) Totaled 1/7/2011
2006 Impala SS (48K)

Mine is about the same, but I usually hit the remote start for 10-20 minutes every morning.

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I'm pretty sure we used replacement OEM plugs, and I left my tire pressure 5 pounds under all around. And yes I run premium fuel all the time lol. After I get my body work done on my Grand Am I'll have the work on the fuel filter done, even tho by then winter will be over and I better see that mpg go up!

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it's winter they use winter blend gas this time of year. also since it's colder the car uses more gas and you mostl likely have it warm up


in the summer i can get 29 mpg combined in the winter the best i got when i drove it was 10 mpg combined

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

Foot of lead?

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2004 Comp G
Parked with a full build on the way! .020 over 10:1 JE's, My Cam and Heads, ZZP S2 IC, 2.8", #80s, Racetronix pump, E85!

no 20 minute warm ups stupid 160* T-stat car sleeps now

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

Haha i cant afford to have a foot of lead with that mileage! What do most people get in the winter time, it's somewhat reassuring that I'm not the only 1 getting shit. And i dk if i mentioned initially, but after I installed the SLP exhaust my mileage during the summer went up to about 18 mpg city and 28 mpg highway.

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Front o2 sensor and clean the MAF? That will help a lot, though they aren't exactly winter weather related.

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Dubs:00 VW GTI VR6, Low and Slow; 91 VW GTI 8v, Restoration Project; 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's; Ex-Girlfriend's 97 GP GT, "Project Pink Power"

this.

I picked up about 5 mpg's when I finally changed mine after 145K miles.

what kind of gas do you use? If it has a high concentration of ethanol or is oxygenated, it doesn't produce as much power when it burns, which results in lower mpg's as well.

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'05 WRX STi- AP Stage 2 tune|Invidia DP|3" Borla XR-1 CBE|TiC super shifter set|DBA 4000 rotors/SS lines|Lots of braces/poly bushings
Sold: 06 Cobalt SS/SC, 99 GTP 245WHP/326 Ft-lbs, 06 R6

damn dude 13 is an unconceivable dream for me
running around 9.1 mpg right now

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Aragorn

my car has a thump stick though

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

Check with a ODB scanner and see if any codes are coming up, You might not see any check engine lights but that's what happen to me but I checked anyways and sure enough the check engine light was out and have a bad ECT which controls the gas mixture. Codes were p0118 and p0650 so check that out and let me know what happens.

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JUST 4 SPEED.

Im getting 24-26 mpg. idk what year yours is but mine is a 05 with the 3800 series 3 supercharged. ive been actually been considering selling mine . .

would having a leaking gas cap cause bad fuel economy? I notice once every 3-4 weeks my car will say check gas cap, although every time I fill up I click it at least 5 times.
The way I get it to go out is to use a rag and wipe the gas cap seal, and the lip around the filler neck, then the light goes off for a while. My car gets around 280miles/tank, 80% of that is highway. I did a tuneup and it made zero difference:
plugs, wires, pcv valve, seafoam, 02 sensor, cleaned MAF and TB. all parts were AC\Delco, car has 122,000km and all the parts I took off were original, never been changed, so I thought for sure it would improve, but I noticed no difference.
My cam'd GTP with a 3.25" pulley got the same fuel economy, this 2006 is bone stock, doesn't get driven as hard either.

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2006 Grand Prix GT

I just did new plugs wires and 180 tsat only gettin 9 mpg? its still the same as before I will change the fuel filter tomorrow and see but WTF?

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JUST 4 SPEED.