Hi VBlaster,
Good to see a fellow E200K owner - Congratulations on the new car,
Im sure you will be very impressed with it as time goes by. A few
things you might want to note or check when driving the car - Wiper
noise during rainfall (quite significant), Check the fit of the
leather trim on the front seatback (The leather on mine was not
connected properly, but this was an easy fix) as well as a fairly
hard to modulate brake pedal. This is due to the directness of the
cars electronic drive-by-wire braking and you will get used to this
after a while! 
In terms of the Avantgarde-Spec rim upgrade, the cost from the
dealer seems quite high for a fairly basic-spec 17" Rim set.
However, if compared to the 18" AMG 5-spokes (retailing for more
then $4900 for the set of four) as well as the fact that the
Avantgarde spec costs 9000$ when applied fully to the car, it seems
like a decent buy. Its really up to you in the end, but the only
real benifit of the upgrade will be an enhancement to the cars
looks as the tire width remains at 225mm wide and a slightly firmer
ride considering the lower-profile tires used.
If you are willing to fork out the cash, go for it. Personally i
have stuck to the stock 16" rims, but this 17" set seems attractive
as even the rims on the off-the showroom E-class are 16" items with
the same Avantgarde 5-spoke design.
