2008 Clubman S has served well from new but recently started being VERY sluggish at takeoff from standstill, especially starting up a hill. No error codes but the ominous half slash engine light appeared. Dealer investigated (for $400), determined the turbo was dead and offered to repair for $5400 - this on a 11 year old car for which the prior week they'd offered $2000 in trade. Car continues to drive OK, albeit sometimes seeming like on only 3 cylinders, but never rough, just kinda weak; on the highway it's fine and the half slash 'check engine' light has gone off by itself, wasn't reset by dealer.
So, several questions: am I causing any damage if i continue to use the car as is, without a functioning turbo? Kinda unsafe at takeoff, frankly, but fine once up to speed. IF I decide to repair myself (I've done engine work, on a lot less-complicated cars) - or at non-dealer shop, for a couple thousand less, what else should I repair/renew when it's all apart? - this is standard shift car with 149K on the original clutch, has never had the timing chain or tensioner replaced, has original water pump, radiator, and indeed has never had any major engine work other than the obligatory walnut shell blasting way back when, at about 30K, and a minor oil leak from some top end tubing a while back. Up 'til now it's only ever been serviced at BMW dealer (always excellent, if pricey) and non-engine-wise the only evident need is 'shocks all 'round and some minor cosmetics.
Sage advice humbly appreciated.

 

I'm curious why the "turbo is dead". Did they offer more info than that? It could be the waste gate linkage (which can be inspected by removing the heat shield to the over the exhaust manifold/downpipe. There are videos on how to adjust and the linkage and inspect the wastegate. My other question would be in the turbo is rebuildable or if you have a pull-a-part near where you can source a used turbo.

Good Luck,
Dupe