when im on the highway...my tank is half way full......i go 70 all the way to fortlauderdale...and back...thats a 50 min drive....and then back....and my gas droped all the way down to jus below the 1/4 full line when goin 70 my rpms are at like 3000.....3200...in that area.....my moms car goin 70 is at 2000.....2200...wuts up wit that?.....is that normal....i herd if i get bigger rims...that would change the rpm to speed thing....not sure tho...i feel like im burnin gas so fast...thats normal?......

 

when was the last time your car had a maintainance tune up.

spark plugs
air filter
fuel filter
oil change
tire pressure
check oxygen sensors
check knock sensor

if your car is outta sync , u will get poor gas mileage. what type of gas do you use, im from s.fl too and i know that with shell, texaco, race track, hess, and marathon i dont get good mileage. there was a shell station around my area that almost got shut down because inspection shows thry were using poor quality gas. i use mobil, exxon, chevron or amaco . take a good look at your car to make sure everything is working properly

 

fill the tank all the way and reset the tripmeter to see how many miles you get to a full tank... you cant really get an accurate reading if your tanks 1/2...

When my tanks 1/2 the gas goes down like nothing.. It seems it takes alot longer for the car to get down to 1/2 from a fulltank than it does 1/2 to empty.

 

my car is the same, if it's a float in the gas tank, depending on the shape of the gas tank the rate at which the float descends may not be constant due to the changing size. for example if the tank is larger on the top, and gets smaller on the bottom to fit around, say the frame or suspension, then it will deplete faster towards the bottom 1/2 of your tank.

hence why it seems to drop like nothing; but you definitely should get a checkup too, because even what you said is definitely not good mileage.

i use 90 octane and drive *A LOT* ... granted I do use tons of gas, but its definitely proportional to the mileage i put on. I can drive from Cape Cod, MA to the norther quarter of NH, and back on just more then a tank of gas; which is MUCH farther then what you traveled.

also the gear ratio is different from your car to your mothers car, which is why her car is only at about 2200 rpm or so; hers is probably an auto and im guessing you have a stick? for standards its common for 5th gear to be above 3 grand at highway speeds

 

give us accruate measurements. @ 70 an auto is roughly at 2600 rpm. ur moms is a v8? every car is different. 50 minute drive isnt an exact measurement of distance. use commas and dots as well !

 

Is your car the same as your moms? Are they both maximas? Is her car or yours a manual?