I don't know if it has anything to do with your problem but my '93LS V-6 developed a crack in a crappy factory weld on the pre-silencer pipe that goes from the CAT to presilencer to muffler I think (the part was one long piece, i.e. part fails it all fails). This was at about 60k miles on mine. It wasn't particulary cheap to replace with the factory part and in retrospect I should have tried to have it welded back together. But as you can imagine the car sounded quite a bit different when replaced.
On to mileage, I wouldn't agree with this one gallon method for calculating mileage. I would fill up, drive for at least 60 miles the fill up again. Mileage = Miles driven/gallons to fill up second time. Sorry if that is obvious. My V-6 auto would get around 22-27mpg (city, hwy).
If the mileage really is that bad and there is really a strong gas smell under the car it would seem you have a couple problems. Exhaust and Fuel/Ignition issues.
Good luck.
WN
On to mileage, I wouldn't agree with this one gallon method for calculating mileage. I would fill up, drive for at least 60 miles the fill up again. Mileage = Miles driven/gallons to fill up second time. Sorry if that is obvious. My V-6 auto would get around 22-27mpg (city, hwy).
If the mileage really is that bad and there is really a strong gas smell under the car it would seem you have a couple problems. Exhaust and Fuel/Ignition issues.
Good luck.
WN