Megan Fox is a Gas Guzzling Gal

Megan Fox fills up on gas after shopping at Ralph Lauren on Wednesday (July 1) in Santa Monica, Calif.

The 23-year-old Transformers hottie also grabbed some coffee with on-and-off-again boyfriend Brian Austin Green.

In September, Megan will play a high school cheerleader who turns into a demon-possessed knife wielding boy killer. The R-rated horror flick is directed by Aeon Flux‘s Karyn Kusama and written by Juno‘s Diablo Cody.

20+ pictures of Megan running various errands in Santa Monica…