Carsharing requires planning ahead of time... Usually, if you
want a car the next day, if its a weekday, you might still be able
to get it... but if its a weekend, or friday night onwards, there
might not be anymore cars for you...
If you know you're gonna need a car during a peak period, you
probably have to book it at least 3 days to a week in advance, just
to make sure you get a car to drive...
If you have to drive quite frequently though, you're better off
getting an off peak car...