Consuming a lot of gasoline vs MPG

[Micape30]

I have an 2007 Aveo and is going 145 miles on 12 galons of gasoline. Octane level in my country (Dominican Republic) is actually very low.

Any suggestions or facts i should consider?

[06T200]

I would make sure the air filter is not clogged up. Also depending on where you live, rodents seem to find the air intake 'resonator box' a very comfortable home and may have built a nest inside the air intake path causing poor drivability and bad mileage. This is a common issue for folks living in the countryside. Other than that, easy things to check are tire pressure, dragging brakes - or possibly a clogged up exhaust can all cause poor mileage. More complicated stuff like engine dynamics, driving conditions, weather, gas quality and many other variables play a part.

[xintersecty]

I have an 2007 Aveo and is going 145MPG on 12 galons of gasoline. Octane level in my country (Dominican Republic) is actually very low.

Any suggestions or facts i should consider?

Well it's time for a math lesson. MPG stands for miles per gallon. So if your total millage on one tank of gas is 145 and your tank holds 12 gallons then write

145 miles
----------
12 gallons

Since the above mathy thing has mixed units they can't divide but you can divide the numbers that comes to 11.15 so once reduced it looks like this:

11.15 miles
----------- or you can write it like this 11.15 miles per gallon.
1 gallon

Bam! Math is easy!

Oh yeah keep track of millage between fill ups and keep records and check your air filter.

[MetroMPG]

Effect unless there's something wrong with the car, then driving environment & driving style have the biggest effect.

EG: if (A) it's an automatic transmission, and (B) you're running air conditioning full-time, and (C) driving short trips in urban conditions, with (D) aggressive driving techniques.... that's a worst case scenario.

Track your next couple of fill-ups and report back.

Track distance travelled & amount of fuel to completely re-fill the tank each time.