Welcome to the site. I have a feeling your not the only one stuck in the large vehicle boat.
Maybe its just me, but I don't think 7 miles (14 round trip, right?) is too far to bike. I would definitly be taking that route if I could.
When you do have to drive, the first thing to do is change your driving style. I'd imagine you can get upwards of 20 mpg in the city even with your large vehicle if driven properly. Check out our list of
100+ driving tips for some inspiration. Also, air up your tires to reduce rolling resistance.