Worst I've had is our '09 Nissan Versa, which had front rotor issues for the first few years (before we ditched OEM for aftermarket) and then the front end needed to be replaced last fall to the tune of $2k.
Not really that bad compared to others. Learned Nissan dealerships suck shit on the island.
Real horror stories go to my brother, though, to be fair, with his choice of vehicles, it's mostly his own fault.
B5 Passat

the usual issues with the B5 Passat
1st gen CTS-V

constant drivetrain issues, especially with the transmission.
and, to top it all off, the worst of the worst,
L322 Range Rover

just ... everything. And, when it goes to shit every 5-10k kms, it costs an arm and a leg.
He loves his money pits. He still has the RR, but it's currently parked indefinitely (when isn't it?). He now drives a POS Neon that he bought for $600 because it's more reliable.