heres what u do first. fill your tank to the top just like u normally would. reset your trip odometer to 0. Then drive around for a couple days. next time u feel like filling up, write down the mileage, then write down how much gas it took to fill it back to the top. divide number of miles driven by number of gallons consumed.

I freak myself out sometimes too thinking i got like 2mpg or something crazy, then i realize i just drive around a little more than i had accounted for. make sure your mpg really is out of range. Something goofy is happening if you are losing gas that fast and you arent getting tons of smoke.

another thing to do is to let the car run in your driveway for a few minutes. check to see if any gas is leaking out of the lines onto the ground. it really doesnt sound like your engine is the problem here.

 

ohhhhhhhh im sorry then it just said you just got a blow head gasket and headers i was like wtf????

 

well i filled it to the top and it hasnt moved passed the full on thegas gauge ive been drivin a good bit3 days know. and doespacesetter headers give upoor gas milage a mechanic told me

 

no, headers wont give u bad gas mileage