The 2007 3.5 Liter V6 Impala we have usually gets the rated 32 MPG or even better on the highway and I can easily see us running this car till it dies as well as it has performed for us.
I realize this is probably off topic from the OP taste in cars... But, we have an older Impala ('01) and it averages 24-26 mpg in city and we have often got 32-35 mpg on long trips barring no strong wind. We plan to drive that until it dies given that kind of gas mileage too...