My previous car was a Toyota Solara. This was a pretty good car but it had an annoying flaw. There was some problem with way the tires were sealed to the rims and they tended to develop slow leaks. So I had to keep topping off the air pressure. When it got too bad I would take it to a tire place and they would do something that fixed the problem for a while but eventually it would recur. Also the car was high mileage and required expensive repairs from time to time. Finally in 2013 (at 216,000 miles) it had a serious engine problem for which I received a $4000 repair estimate. So I replaced it with a Toyota Camry my current car.
The Solara was a variant of the Camry so there isn't too much difference between them. The Camry had about 34000 miles on it when I bought it (it is now approaching 72000 miles). This is the only car I have owned with less than 100,000 miles on it and it has been pretty trouble free which is nice. The Camry also gets better highway mileage than the Solara. The gas tank is the same size so the range is greater. The longest distance on one tank of gas I managed with the Solara was 536.5 miles (Salt Lake City to Denver) in 2011. I soon exceeded this with the Camry (541.7 miles in November 2013) and while on vacation last month set a new personal record by going 626.2 miles on one tank.
The miles per gallon (mpg) achieved between fill ups seems to vary quite a bit even when I am driving almost exclusively on highways. On my vacation last month my mpg varied between 33.3 and 44.8. Measurement error could be part of this, I fill the tank until the pump shuts itself off and I expect there is some variation in how much gas is in a full tank. Elevation change is clearly a factor, my record distance was aided by a 5000 foot elevation drop which I estimate saved about .8 gallons (compared to no net elevation change). Running the AC will reduce mpg as will traffic tie ups. Average speed affects mileage and when driving long distances in the same direction it seems plausible that you could have a substantial average head wind or tail wind which would also affect mileage. Anyway enough things lined up right for a new record.