Low MPG (20 MPG)

#1
Last fillup I reset the trip meter and yesterday I filled up and the trip meter said 61.4 miles and I put in 3.038 gallons of 87 gas. That comes to 20 mpg. The tires are at 30psi, oil changed recently, clean air filter, 87 gas from shell and bp oil gas. Its a 2010 with 43k miles on it. I did use the AC a couple days but I still dont know why the mpg is so low. I dont floor it at all. It is an automatic trans and rev it gradually and it shifts at 3000 rpm. Any suggestions?
 

Ted

New Member
#2
20 mpg is low; however, I think you're not using a good system. Filling up after 61.4 miles is too soon. Go for at least 300 miles and when you fill up don't top off, just let the pump snap off. Do this each time and you should get truer readings. Also, 30 psi is too low for the tires. They probably should be 32 psi and you're better off using 34 or 35 psi.
 
#3
Switch petrol stations, fill 'er up like Ted said, and along with the computer readings, old-school it with pencil and paper.

Once you've gone through a tankful, choose a different brand of petrol, and do the test again.

If, after that, your readings remain at a combined 20 mpg (average is around 30 or so), you'll want to take it in for a diagnostic evaluation.
 
#4
Low MPG

Last fillup I reset the trip meter and yesterday I filled up and the trip meter said 61.4 miles and I put in 3.038 gallons of 87 gas. That comes to 20 mpg. The tires are at 30psi, oil changed recently, clean air filter, 87 gas from shell and bp oil gas. Its a 2010 with 43k miles on it. I did use the AC a couple days but I still dont know why the mpg is so low. I dont floor it at all. It is an automatic trans and rev it gradually and it shifts at 3000 rpm. Any suggestions?
Are you carrying any cargo? What weight oil are you using? Has the vehicle received proper maintenance? I would bring up tire pressure to 35 psi. I can tell you for sure that it is not impossible for you to be getting such low milage depending on your driving habits and your answers to the above questions.

I have a 2012 Corolla and I am averging 22.1 mpg however, my trunk is full with my tools and I am using a slightly thicker oil 5w-30.

As far as calculating your mpg, try going through 3/4 of a tank at least before you perform your calculations. If you top of your tank, make sure that you top of your tank again so your next calculation is accurate. If don't top of your tank, do the same for next fill up. Try to use same gas station and pump. Topping off your tank as far as it can go may cause some fuel to evaporate out ( as much as a gallon) and can lower your mpg.
 
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