Not very many options will meet their criteria. I am guessing they want cheap maintenance and good reliability. That puts Japanese vehicles on my mind. Although not very big, I would suggest any of teh following:
Accord, Camryy, Galant, Mazda 929.
What about an older Passat? What do you guys know about those (I know the newer ones have reliability issues)?
The problme is tha they are looking for such a high gas mileage. If they don't drive too much, then it really shouldn't be too important. In that case, they can look into Buicks and Chryslers.