I'd taken both sets of keys with me so I could back my car down the driveway, then back out Erica's car, then move the cans into position, and then put the cars back. And I looked at Erica's car. And the blue rolling cart that was in front of the ladder that was between the driveway and the spot where the cans go.
So I picked up the cart, moved it out of the way, and rolled the cans into their accustomed spot in the garage without having to do the automotive shuffle.
Erica's car is a Ford Fusion. Mine is a Ford Five Hundred. That apparently makes all the difference.
Maybe I should get a smaller car. :)