The first station Tara stops at charges $3 for a gallon of gas, so for her 12-gallon tank she spends 12*3= <<12*3=36>>36 dollars
The second station Tara stops at charges $3.50 for a gallon of gas, so for her 12-gallon tank she spends 12*3.5= <<12*3.5=42>>42 dollars
The third station Tara stops at charges $4 for a gallon of gas, so for her 12-gallon tank she spends 12*4= <<12*4=48>>48 dollars
The fourth station Tara stops at charges $4.50 for a gallon of gas, so for her 12-gallon tank she spends 12*4.5= <<12*4.5=54>>54 dollars
Now that we know all the individual amounts, we add 36+42+48+54= <<36+42+48+54=180>>180 dollars in gas in total.
#### 180