The dealership called me yesterday afternoon to tell me my car was ready. The serpentine belt had not fallen off at all, but I was out of refrigerant, which had caused the air conditioning to turn off. They weren't certain why the car had died; it started up fine for them - maybe something about the compressor. Moreover, they couldn't find the leak. (And a leak it had to be - my oil had been changed 1000 miles ago and all fluids topped off.)
I got on the freeway to drive home, and after about a mile the air conditioning quit. At the next exit I pulled off and called the dealership. They told me to come back. I didn't feel like stalling out on the freeway, so I took back roads. Under the hood the engine was making a rattling noise. Then at the last traffic light, my brakes stopped working. The emergency brake worked, but the car stalled and wouldn't start. I rolled it around the corner and called the dealership again. A manager and a tech came out, and after about 20 tries it started and barely made it back. (I chose to walk.)
So now I was out of coolant, but again they said they couldn't find the cause of the leak. This time the theory was water in my gas tank - the gas light had just come on. I went to the gas station across the street (prices having gone up 30 cents from when I first came in to pick up the vehicle) to fill up. Not exactly feeling secure, I moved my car forward a few feet after fueling. The car was leaving a trail, much like a slug.
I took it back to the dealer, even though they were closing. They were suspicious it was nothing - some coolant had spilled when they refilled it, and they thought it was just the spill dripping. Still, the manager grabbed a master tech who was on his way out to look. After just a few minutes, using no tool more advanced than a flashlight, he figured it out.
A clamp on a hose had broken. When the car was cool, after sitting for a while, nothing happened. But after driving a while pressure would build up and the fluid would leak. All they had to do was replace the clamp.
And why didn't the first two mechanics to look at it notice this?