Easy speedo check: Two cell phones in two cars in the middle of the night (on wednesday). You should have the road to yourself for a side-by side. Use cell phones to cross-talk and check what each vehicle's speed indications are. Don't be surprised at deviations of up to 2 MPH.
HERE'S a good question: Are your wheels stock? Bigger/smaller will throw off everything having to do with speed/distance instruments.

 

haha!

 

mine does the same thing.its not that big of a deal...just know when your on e...its not really e.loli just fill it up when its on e,but it always only takes 8.5 to 9 gallons in a 11.9 gal.tank.there is a grimlin hiding 2 gallons at all times.

 

i was sooo comfortable thinking i has a 2 gallon fuel line...my worlds upside down now.lol