old cars now-when tuned they wear out engines fairly quickly[it is an old design to be fair] engine blocks/cranks and heads are expensive-as are gearboxes/rebuilds for same
however normal repairs are cheap-along with the servicing,once you have a car "up to scratch" it shouldnt cost fortunes to run as standardish
to be honest though they are well past the age where they are a nice daily drive-better as a weekender,i used one daily year before last,now use a 335d and have a different classic for weekend use