How bout this....
She dumps the car. I'm leaning towards she dumped it to get stolen, why she ran it out of gas is beyond me, but whatever. She probably dumped poor little Caylee a few days prior, like around the 24th when she starts telling people about the smell in her car. Anyway, she takes a few days to try and get rid of the smell, figures out she can't get rid of it so she dumps her car.
I think she ran it out of gas, because as it's been said before no one has come forward to say they were the ones who pushed her into the lot. ALSO... mind you her car reeks. I don't think she would want anyone that close to the trunk. AND if she was dumb enough to let 2 people close to the trunk to push it, and gave the old squirrel excuse. I think that incident would stand out in their mind to the point that they would have talked to the police by now.
As far as the food... Someone said it's apprx. 7.5 miles to her parents home. At 7am (or before) it's not too hot out, she seems to be in shape. I bet she walked home waited for her parents to leave, showered the funk off, took the food, and got a ride up to her car from someone else. Why they haven't spoken up??? Don't know. Or she found some cash at the house and took a cab. Called Tony on the way. Ta Da! KC's at her "broken down" car with frozen food when Tony pulls up.