If you slam into another car,
you're liable for the damage to the
other car.
Most car renters include liability
insurance in their rates because if
you weren't able to pay, they could
be held responsible (since they own
the car). So they're covering themselves
as much as you.
Turkish rental agreements usually
state that liability insurance is included
"at the minimum amount
required by law." I suppose
this means if things go really badly,
you could be liable for some amount.
But let's face it, usually we all
just accept the amount offered (implicitly
or explicitly) in the car rental contract
as sufficient and let it go at that.