According to the EPA, the 2009 Acura MDX averaged 15 miles per gallon in city driving and 20 miles per gallon on the highway. That gives the Acura MDX a combined score of 17 MPG. Acura recommends premium grade gas for the MDX. With its tank size of 21 gallons, a full tank will cost you around $40 and can take you up to 321 miles. The cost to drive for 25 miles in a 2009 Acura MDX would be around $3, more or less.