I'm filling up with my gas light on and my car says I've only driven 170-180 miles I see 200 is horrible I've never hit 200 miles in one tank....

I have mods.. see in my Sig... I use premium every time. I mean im a little hard on the gas but I don't see that being the huge decrease.

 

Sounds like it could be O2 sensors. Your mileage cuts in half with bad sensors, but may be working just well enough to not throw a code.

 

I think the Gs have problems with their gas guages. I'd try seafoaming the car then put some Redline Fuel system cleaner in and reset your ECU. It helped increase my mileage by 100 km per tank

 

Don't go by the gas gauge.

Top the tank off, and when full reset your trip odometer to 0 miles. Drive around. When it's time for gas, go back to the SAME EXACT pump and refill the tank. Record the number of gallons it took to fill the tank, and the miles you drove.

Repeat it a few times, and that should give you an accurate picture of your fuel economy.


The reason for using the same pump is because the nozzles can be different and turn off at different times. Using the same pump eliminates that variable.

And yes, the gas gauge sucks. It will sit at full for 100 miles, and then drop like a rock after that

 

+1 to Mustang. Mine never gets to F, even if I'm spilling gas out the tank. I always (used to, different story) go by distance driven, not the gauge. You can also go by a little deductive logic when you fill up. I've filled up as soon as the low fuel light pops on and I've gotten a little over 15 gal in the tank. This means the light pops on with between 4gal and 5 gal left. In a 20gal tank that's between a quarter and a fifth left which seems like a lot to me. Even when the gauge is completely on E I've gotten only 17-18 gal in the tank which means there's 2 or 3 left.

The only way (aside from what Mustang suggests) to see what you can really get out of the tank is to fill it up, reset the odometer, then drive it till THE TANK is empty (not the gauge says your on E), then do some division... Obviously, you want to have a lawnmower 3gal tank in your trunk or something since you just ran out of gas LOL

 

Perfect answer! ^ Patrick, If you're careful and fill it up to the top of the neck it won't matter where you fill up or which tank...you know it's full! You could use the Redline injector cleaner but forget about using that Seafoam cleaner!!
Gary

 

funny my ses came on and its an 02 sensor. I'm bringing my car in for new brakes so im going to have them replace all my o2 sensors and I will start to calculate my gas mileage with that method thank you!