Good used Mercury Grand Marquis if you can find one.
Like driving your living room and mine gets 23.7 mpg each and every day of my 82 mile trip on backroads and freeway in stop and go driving. Hardly varies by more than 2 or 3 tenths. You can punch it an go like a striped arsed ape if you need to.
About 27 to 28 mpg on the highway at 75 mph all day long.
The average is for the last 32,000 miles or so.
Relatively cheap to buy, cheap to maintain and cheap to insure.
I bought it when I decided I was no longer going to wear our my Dodge Cummins when I returned to the US full time and had to make the daily slog again. The truck got 21 mpg and I could not bear to get a rice burner that got nearly the same mileage with the huge step down in comfort and safety.
It is also a car you don’t have to get emotionally involved in.
You made me weep remembering my 1997 Town Car, the last real Town Car.