Horrible gas mileage
 

ok guys, so its been 3 weeks since I bought my car, a 97 protege lx with 122k kms. I took it on my first road trip and time to see kinda highway mileage i can get. I got a measly 500 km (310 miles) on the full tank. The tanks can hold almost 50 liters from what i have read. So its basically 13.2 gallons. so 310/13.2 gives me 24 mpg, THATS HORRRIBLEEEEEE. I just had a tuneup done on it, the filter is clean, and yet im getting V6 mileage, what gives? My 93 corolla gave me 400 miles on a smaller tank. Can others poston the mileage they get?

Your method of calculation is invalid; the size of the tank is completely and utterly irrelevant when it comes to determining your fuel economy. What you need to do is fill up, drive until the gauge hits "E" (if not a bit beyond), fill again and then use that gallon/liter figure to calculate your economy.

Note, this procedure will give you a rough estimate as different pumps "click-off" at different points; if you want a much more precise figure, repeat the above procedure for five consecutive tanks of fuel and base your calculation on the total distance driven compared to the volume of fuel you bought during your second through sixth fill-ups.

Ive always been used to filling up all at once. I do not fill up until the gas gauge is below E. I like to see how much Im getting per tank. I understand what you mean but trust me, I am filling the tank all the way up. I know that the pumps have built in mechanisms to stop when they think its full but I keep pumping until I can see that it really is full. Ive even managed to put a gallon at some pumps once the mechanism kicks in.
I have been doing this since the day I bought the car. The figures i gave you are non stop highway figures, its even worse with a mix of city driving. Overall I am not impressed at all with what im getting. The thing is rated at 30/37. Im not even getting 30 on the highway

Regardless, by using the maximum capacity of your tank and not the actual amount of fuel you pumped (after the drive), your numbers will be grossly inaccurate. Fact of life.

As for filling your tank until you can see the fuel; in most states what you're doing is illegal. The legality of the issue aside, what you're doing is both wreckless and will eventually render your evap system inoperable, and as soon as that happens your car will become a mobile hydrocarbon pollution factory even when it sitting quietly in a parking lot.

Well I knew that it wasnt the best practice but I dont overdo it. I pumped almost 49 liters in my last fillup and capacity is 50 liters. So im def calculating the right thing. Regardless, a full tank should def net me a lot more than what im getting

thats why i got rid of my mazda in the city it was only geting about 350km of a tank whats all done to the car if you have anything done? i had an intake on it it was a wepon r intake and the intake was designed poorly which because of the lack of air actually managed to remap the fuel map so when you hit the gas it would cut the fuel back so there was no power at all but while driving normally it just dumps gas.

Wouldn't it have been cheaper to simply put the factory intake back on the car?

You put 49 liters into a 50 liter tank? Yikes; not only are you corrupting your evap system, but it sounds like you're running your tank low enough to expose your in-tank fuel pump to over heating.

As for your fuel economy, when you recalculate using the actual fuel consumed and not the size of the tank, what kind of economy figures are you coming up with?

Actually cutting the fuel back is a trait of these engines on these cars i think. Starting off a light, I usually featherthe throttle to save on fuel, every damn time it short shifts out of first even when im accelerating and then I have to go harder onthe throttle to gain speed and then boom, it downshifts to first again, I hate that about this car. I have a stock air box, its a beater which me and my wife are using, not gonna spend a penny more on it than regular maintenance

I only did this once to really get a true calculation of what mileage im getting and its pathetic. So wont be doing this anymore since I know I can barely get 25 mpg going non stop on the highway for the full tank. I was just wondering if it was just me or are others getting similar numbers

it would have been cheaper if i knew that was the problem i didn't know it was the problem until i talked to a tech at aem who showed me how picky the ecu on mazda's are and if the intake is not designed perfectly it will cause the computer to remap the fuel. once it remaps it takes longer than a few days for it to learn that the air supply is back even if you reset the ecu. so when we did swap out intakes there was no difference. when we first got the car it was doing 700km per tank after it was topping out 350km a 1.8l motor should not be doing half the mileage my 2l turbo car is doing.thats why we ended up getting rid of it.