MPG for my 89 carbed 4 Speed

[collegeboi]

So during the past few months, I started wondering my actual gas mileage for my Festiva.
I always thought that I was getting about 30 mpg mixed. So i did this test.
(PLEASE LMK IF MY CACULATION IS WRONG.)

The tank was on E so I decided to put 20$
Mileage before fill up: 85,835
20$ (87 octane) @ $2.89 = 6.92 gallons ( rounded to 7)
Mileage after(E)= 86,090

So 86,090-85,835= 255

255/7= 36.42 mpg

So 36.42 mpg driving mixed heavy on the pedal. I never drive under 70 on highway and always stomp the pedal at stop lights.


Do you guys think this is decent mileage. I will compare when I do a tunr up but probably won't see a difference.

[deathegg]

First I have to ask why you rounded up to 7? I would want it to be as exact as possible, so I use the actual figures and not round up or down.

That being said, I have an '88 carb 4-speed (204,000 miles) and get about 35-36 around town, with some highway miles thrown in. IMO your m.p.g is right on the money from my experience. I'm sure you'd get better mpg if you didn't "stomp the pedal at stop lights" (I assume you meant green lights?). Relax! Don't be in such a hurry to get to the next red light! You'd probably get near 40.

[88FestivaLX]

My 88 5 speed gets between 40-44 normally. Thats normally driving 45-60 mph on local roads and 70-75 on the highway. My normal drive is about half local roads and half highway. I know mines a 5 speed, but just thought I would throw it out there. I was being conservative on a tank a few months ago and got 51 mpg, ha.

[getnpsi]

rounding isnt the thing to do. Also you cant really be accurate between fillups until you fill it FULL then drive half tank and fill until the gas pump stops again. Im sure you are close but filling on non-level ground or a really hot day will change things a little.

[25Horseplay]

My 89 carbed 4 speed has been averaging 42 MPG mixed driving conditions since I got it.

[spiko]

Now that everything is running right with mine, I need to check what mileage I'm getting

[collegeboi]

I think I need a new o2 sensor because for 20 years it hasn't changed.

[bhazard]

First off your calculations probably ARE wrong if youre just putting like $20 and not actually filling the car. Calculating mileage is really easy.

1. Fill the tank up (I fill til the pump clicks off and then round to the next $.25)
2. Reset tripmeter
3. Drive for a while, like at least down to half a tank, the lower the better though.
4. Fill tank again, the same way as last time, and preferably even the same pump. Fill it, dont just stick $10 or $20 in.
5. Now take your miles on the tripmeter and divide it by the gallons it took to fill the car up. Youll have something like 328.3 miles and 7.641 gallons, which will end up being 42.96 mpg, or just round that to 43.

Now if youre running tires that are larger than stock (most of us) youll have to correct the odometer reading. Go to http://www.miata.net/garage/tirecalc.html and put in your stock tire size (145/80/12) and your current tire size (for me 175/70/13) and for example it tells me my speedometer reads 7.2% slow, so multiply your odometer reading by that number (328.3 x 1.072 = 351.9376, or 351.9 rounded). Now you gotta take that 351.9 and divide by your gallons (7.641) and you get 46.05 mpg.

So there you have it, try that next time.

Im actually in a little competition at ecomodder.com right now with a guy that has a metro he gets 55-60 mpg with.