Extended warranty experiences

I have a sprinter used for my business' deliveries. Based on my experience with both the frequency and cost of repairs I will NEVER buy another Mercedes product again. It's in the shop (certified Mercedes shop) as much as it is not. Four years use, 180,000 miles and repairs equal half it's purchase price. (And it's purchase price is quite a bit more than its competitor's) I have a second delivery vehicle, a Nissan NV, and it is a dream. I guess they're both dreams but the Mercedes is of the nightmare type. I bought the Sprinter because I heard all the hype talk about getting 400K miles with little troubles. Totally wrong. Now almost every Sprinter owner I talk to regrets their purchase. Could that have something to do with my area being colder than most of the US? I dunno. But that is my experience with Mercedes.