Because the dealers and their "techs" are rewarded for fast work not quality work- the faster they do the job the more profit they make. You would think VW would counter this by rewarding dealers for quality work, but this does not seem to be the case. As a VW owner since 1985 I can personally attest to VW's crap dealer service. I've tried almost all the dealers in my area and they all suck. Some recent examples from 1999 VW Passat V6:
- My car came with "free maintenance" (read 4 free oil changes) for the first 24,000 miles. Afterwards I changed the oil myself. First time I changed the oil I noticed the plastic belly pan under the car was missing 1 nut and 2 fasteners. Later when I had some warranty work done I mentioned the missing fasteners. When I picked up the car they said they didn't see anything missing. I looked under the front of my car and showed the service advisor the missing nut. He said the mechanics had left and to bring it back and they would fix it while I waited. I was really ticked off. Something so very minor and they can't even get it right. As I was walking back to my car to leave, I noticed something on the ground. I picked it up and it was a nut with a built in washer. To my amazement, it fit the bolt securing the belly pan. I actually fixed my own car in the parking lot of the dealer!
- I had the dealer replace my front brakes. I asked the dealer if I could supply my own brake pads because I didn't like the VW pads that came with the car (they caused a lot of brake dust turning my alloys black). To their credit, they said fine. When I picked up the car they warn me the pads I supplied didn't fit very well and they recommended sticking with the VW pads. I take the car as is and the first time I use the brakes I was like WTF??? The brakes made a strange vibrating sound and their effectiveness was half of what it should be. It was criminal of them to even let this car drive off the lot. They took a car that had worn brakes but still stopped fine and "fixed it" to the point where it would barely stop at all! The next day I bring it to Meineke and surprise, surprise, they tell me the pads were not installed correctly.
So, I here you brother. If they can't replace a cabin air filter without crushing it, how can you trust them to perform an important engine repair? (Answer: you can't). In my case if they couldn't be trusted to replace the fasteners they removed for an oil change how can I trust them with my a critical item like my brakes? (Answer: I can't).