In my area this weekend the airport Enterprise is $11/day, as is the Airport Alamo. Both unlimited miles. The difference with Alamo is you can stack a $15 off 3 day coupon on that deal which more than makes up for the extra airport fees. Also with Alamo you can throw in an airline number and get some miles (albeit the fee they charge eats up half of the value of those miles).

The 12.99 seems like a bit of a non-starter.