It took them 10 hours to figure out it was a bad oxygen sensor, and then another 2 to fix it.
I think someone was getting scammed here. Since it was a warranty repair, maybe the dealer was scamming the factory warranty program somehow.
The engine ran fine, happily got between first and second, and had no problem with fifth while we were on the highway. It was only after the light came on and I had to slow down to turn on the road to the place we were staying at that it started to struggle.
And sure, I could have driven it, but it probably would have been a two or three hour drive topping out at 20mph... hence the tow.
Given that O2 sensors aren't exactly expensive to replace, it seems like an odd scam.
That process is the same first step they would have taken anyway; I mentioned what I did to make sure they would have the right part available. As it turned out, I still had to wait an hour and a half once they figured it out because, lo and behold, they didn't have one and had to go out to get another.