Depends on a few things.
First off. If it’s my car or not.
If not – Not a bunch I could do anyway. Who says it’s not a dealer loan car, etc?
If so – Depends on what I took it in for.
A transmission issue that I knew needed a warmed up road test for – I’d roll the window down and ask him how it’s going. (Though I might still bring it up with the service writer/mgr. for their thoughts on the matter.)
An oil change, new headlight, replace the wiper motor… (not like I’d take it in for any of that
) or something like an A/C service – I’d be a bit erk’d, and would for sure bring it up with the service manager. I might even call them from the drive through and ask: “Any idea why my car is being used for bank runs today??”
Then I’d let them know how much (per mile) I rent the car out for such things.