Car seat and rental cars - can you trust them to be there?

[reren]

Anyone have any advice about whether its better to take your own carseat on the plane or rent one w a rental car? Im worried about getting to rental pick up and discovering theres no seat available? But can you just put a car seat through the hold? And if so - is a maxi cosi for infants just as safe strapped in (usually we have it set into the holder thing that is attached to seat)?

[echo]

simular question here