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miles per gallon?

I just bought a 2006 GP GT S/C and only getting 20 city and 23 highway. When do plugs need to be changed? I only have 50,000miles on it. I drive mostly highway and my average is 23 right now. I have a pretty soft foot especially on highway , but I did test it out a couple times. Id like to do a couple performance mods but as a daily driver I need to work on the MPG first.
 


MyPrixGT06 said:
When do plugs need to be changed? I only have 50,000miles on it.
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Well, according to GM the OEM plugs should last 100k. I say check them, the front ones are easy to get to. And if in doubt just change them, fresh plugs should help your mpg. It really doesn’t matter what plugs you use, there is no performance difference. The expensive ones last longer is all. I personally use cheap AL606s, because I like to change them and see how my engine is doing every 20-30k.:th_thumbsup-wink:
 
91 or higher is for the supercharged cars, because of the compression and to lower the kr.and to prevent ping.

supercharged cars should NEVER run 87, but if you do it be accident, then its ok, just drive a little bit or half tank, then fill up with 91 or higher.

to explain your MPGS, id change the plugs, and maybe seafoam it first and maybe change your o2 sensor.
 
Fivefingerdeathpunch said:
91 or higher is for the supercharged cars, because of the compression and to lower the kr.and to prevent ping.

supercharged cars should NEVER run 87, but if you do it be accident, then its ok, just drive a little bit or half tank, then fill up with 91 or higher.

to explain your MPGS, id change the plugs, and maybe seafoam it first and maybe change your o2 sensor.
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My user manual says 87, but is tune for 91(I don't know if it used the word "tuned", but something along those lines). I have friends with BMWs and such, their cars say on the gas cap "premium only", why doesn't mine if its so bad? Ill probably do plugs ASAP. Whats the gap on 06 GTs?

Sorry for stealing if I'm stealing a post, but I think this is still pretty close to topic
 


Using 87 compared to premium is what...a $3 difference at the pump? It'll basically save you the money in the long run because on 87 that thing is going to be knock knock knockin
 
I do a 60 mile commute to and from work. Only about 4 miles are city rest is highway. I used premium and was getting 27+ mpg when I reset my mgp average, but when i get to the 4 miles of city driving the average goes done to 22 and Im averaging 22-23 mgp and about to refill the tank. I know the computer isnt 100% accurate( I used good old calculations before and was about 1-2 mgp less then what the car said). It seems like this car does great on flat roads but you give it a hill and your gas gets sucked out. Anymore help?

Getting suldge in coolant flushed today and might go get spark plugs while I'm out.
 
if it helps I get an average of about 20 MPG on my GTP and thats half city half highway

also check your fuel pressure regulator .. that was bad on my GT and it was getting awful MPG in the city until I fixed it
 


Some auto shops (Oreillys, Autozone, Advance Auto, Napa, ...) allow rental tools, you just need a Fuel Pressure Tester, it hooks to the fuel rail. Very simple to use and understand.

My 99 GTP with 83k gets 16/17 in town, 27/28 at 75mph, 30 on the dot at 65mph straight highway\
It really just depends on how you drive them, but i think you need a tune up or something. When was the last time you replaced the fuel filter or air filter. If your using 87 octane religiously the filter may be getting stopped up a lil and reducing your fuel pressure
 
TLSheff said:
Some auto shops (Oreillys, Autozone, Advance Auto, Napa, ...) allow rental tools, you just need a Fuel Pressure Tester, it hooks to the fuel rail. Very simple to use and understand.

My 99 GTP with 83k gets 16/17 in town, 27/28 at 75mph, 30 on the dot at 65mph straight highway\
It really just depends on how you drive them, but i think you need a tune up or something. When was the last time you replaced the fuel filter or air filter. If your using 87 octane religiously the filter may be getting stopped up a lil and reducing your fuel pressure
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I just bought the car so I don't know when the last tune was and dubt it ever was. I have 50,000 miles. I'm planning on changing plugs and posibly the fuel filter. The air intake looks new. I'm planning on putting a intake.

what is the psi on a S/C 06 supposed to be?
 


MyPrixGT06 said:
I just bought the car so I don't know when the last tune was and dubt it ever was. I have 50,000 miles. I'm planning on changing plugs and posibly the fuel filter. The air intake looks new. I'm planning on putting a intake.

what is the psi on a S/C 06 supposed to be?
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I would put on a new fuel filter and start running 91-93octane, consider new plugs and wires, putting on an intake will probably DECREASE your mpg (you end up wanting to hear the whine more and thusly forget to baby the car, and lose mpg hehe)

as for psi, i believe its 6-8psi *could be wrong* but the difference on your SeriesIII (Gen V) SC vs say my SeriesII (Gen III) SC is alot. the CFM (flow) is greater at the same psi for the Gen V but that is a whole new conversation. :th_winking:
 
i was getting like 14 mph city when i bought the car, got a tune up new plugs, threw on a thrasher intake, fuel pump, new 02 sensors and my mpg shot up, now i get 17.5 and about 27 at 65mph on the highway, and thats with a broken EGR, which i will be deleting all together :)
 
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