Hi everyone,
I have a stock 2002 Z28 which has about 30,000 miles on it. I do a lot of my driving around the city and some on the freeway and most of the time I get around 200-220 miles on 12 gallons of gas. Of course on the freeway, the 12 gallons would give me around 340 miles.

Off late however, I noticed that the mileage dropped to around 170 miles for the 12 gallon which is like 14 mpg. I know I have a V-8 and ain't supposed to be complaning about mileage, but it's just dropped from how it was and that concerns me.

I change my Mobil synthetic oil every 3K and don't miss on any service intervals. I figured I could ask you folks if anyone has had a similar experience.

Thanks
Aby

 

Clean air filter, new fuel filter, change plugs, check tire presure, run some top engine cleaner or seafoam, possibly change PCV valve. Se if any cat related codes are showing.

I only get below 20 mpg when I've been racing.

 

Thanks Greed4Speed,
I am going to run through each of those items. Mine is an M6 as well. And you get 20 mpg when you are racing? wow that's cool. It's just yesterday that I also realised that one of my tires (on which i check air pressure every month) had it's balancing plugs gone. I don't know if that has anything to do with this whole thing.

Anyway I'll let you know on how it goes.

Thanks very much for your help.
Aby

 

No, I only get below 20 mpg when I've been racing, or setting in traffic forever.

 

Nice that your car is stock, makes it eaiser to find problems

I'd say just do the basic general stuff, like was said. Also check fuel delivery, see if that's being clogged anywhere. 02 sensors also. Has the car thrown any SES lights?

 

Run a bottle of fuel injector/system cleaner also. Whats the average engine temp? Anything below 180 degrees will degrade fuel economy.

 

Hi Strahley, V8 salyer,
Well the SES light hasn't come on. I don't know about the O2 sensors or the fuel delivery. I had gone over to the dealers for a 30K service and those folks over there had me poorer by 500 saying that they would replace the fuel filter, check the PVC valve etc. They did all that. I doubt if they would have checked the spark plugs or the sensors or the delivery system. They must have just done some inspection, replaced the filters and topped up the fluid.

After all this, there seems to be no difference. I am beginning to wonder if this thing happens only when I switch on the air conditioner (never happened before), but I am going to do a run without the A/C and see if there is any difference and if there ain't, well I am going to get myself the service manual and a good tool set and start working myself. Can't afford to spend all those big bucks everytime I get into the workshop. But I am going there once more and will ask them if they checked the points that you mentioned.

Thanks for everything..will keep you posted.

Kind Regards
Aby