hi mate
the ST170s are bullet prof there are a few things that needs to be done to them which are the timing belt and pulleys need to be changed at 100.000 miles as do the clutch and dmf ( but the clutch can go when ever)i had mine done at 100.000 miles.1 common fault with them is that the clutch master cylinder starts
to leek and green fluid will seep onto the floor(under the clutch peddle) the rear wash pipe just under the head lining can come apart and is a twat to get at to put back together.the heat shields can come lose and rattle.lamber censors do give up at some point.and need to be changed.other than that they are a great car had mine going on 4 years and never had such a great car love it.as for the mileage thing your talking about the steering wheel should be like new not worn on the top (dont sound good) what you need to do is check that the screws which hold the cover that sits around the clocks are black in colour and not silver in the middle if they are that means 1 of 2 things 1 being the clocks have been changed (if so when & why) 2 the car have been clocked in which case walk away mate LEAVE IT WELL ALONE if i
can be of any more help the please fell free to ask GOOD LUCK