I work on hackney taxi's every day, and with the exception of that old carina, pretty much everything mentioned so far is low mileage lol, not unusual to see them break the million mile mark, they're expected to do 500,000 on original engine, any less and the drivers complain, most complain even if they do a million miles and burn a bit of oil(miserable bastards), I look after a fleet of TNT delivery vans as well, and there's a couple with over 300000 on them, and they aren't due to be changed for over a year yet, should see 400000 out a couple before they go, just goes to show that if looked after then mileage is irrelevant as we also do vans with 50000 that are burning oil already
A lot is definitely down to how it's looked after( driven and maintenance)