You've done all the planning and spending, and you're finally embarking on a much-needed family vacation. You've even reserved a rental car with a car seat for baby, so that you don't have to lug yours. So smart! Unless it's not, of course. While rental car companies offer infant and toddler car seats as an "added convenience" (and at an additional charge, of course), it turns out that the reality may be worse than you could've possibly imagined.