So the past few weeks my gas mileage has decreased dramatically. and by dramatically I mean, sitting in a parking lot in park and it goes down 3 bars to empty. any ideas on whats going on?

 

So, what is your average mpg? Fill up the tank, reset trip meter, drive, fill up again. Divide miles by amount of gas you put in the second time (make sure you fill it up all the way again).

Just telling us that the gas mileage went down doesn't help us much. Anything changed on the car, modifications, how long have you owned the car, miles on the car?

 

You're aware that when your car is idling (not moving) you get 0 mpg... so that might affect it just a bit. Maybe you should stop just sitting with your car on so much

 

What type of gas do you use? Maybe dirty gas is causing fuel injectors to be clogged? I always use Chevron

 

The OP needs to chime in with average mpg. Again, we can speculate all we want, but until he gives us more info, there is nothing we can accurately suggest that is wrong with the car.

If he hasn't come back yet, I wouldn't expect him to. Makes no sense though. Takes the time to join a forum, use it for asking a question, but then don't come back? /rant