First, figure out how many gallons of gas Marcus bought by multiply the gas tank's volume by the number of fill-ups: 20 gallons * 2 = <<20*2=40>>40 gallons
Then multiply that number by Marcus's fuel mileage to find how many miles he drove: 40 gallons * 30 miles/gallon = <<40*30=1200>>1200 miles
Then add that amount to the initial number of miles on Marcus' car to find the final number of miles: 1728 miles + 1200 miles = <<1728+1200=2928>>2928 miles
#### 2928