New boots like a new car..
I have a 2010 520D with just under 80,000 miles on the clock.
The car came with Continental OEM tyres when new and when they were replaced at 34,000 miles the fleet company fitted Bridgestone Potenza's. These tyres seemed really noisy compared to the Conti's and today 35,000 later I had Conti's fitted again and I can't believe how much nicer the car feels and sounds. It feels like a luxury car again.
I also seem to get a huge amount of mileage on tyres in this car my friend with an Audi A5 only gets 11000 on a set. He does say I drive like a pussy though.
Anyway the lease is up in a couple of months so think its time to start speccing up a new 5 Series.