The (my) Prius gets better gas mileage than the (her) Jetta does.
Alice commutes. I don't. There is a parking discount for hybrid drivers at Expedia, which will save us an additional $75 each month in addition to the gasoline savings. This makes it the better choice for her commute from from both an economical and environmental standpoint. It just makes the most sense. It is better for us and the world if she drives the Prius to work instead of the Jetta.
Hey, that's my car!