I have no idea where you live or if you might need a second car.
Having said that, and if you (or she) don't get in a situation where you both might need a car at the same time (going to work), then I would suggest a bike. If cost is a factor, look at Yamaha cruisers, for example. Great bikes, lower cost than say a Harley and I get around 50 to 55 MPG on mine...and a lot of folks think it is a Harley the way it's all decked out..