It has been a few years, but I recall bringing my SO’s Focus into the Doenges dealership not long after we moved back to my hometown which was about 8+ years ago.
I was too busy to do the OC on her car, IIRC, the price was the advertised $9.95 but the service writer did her darnest to up-sell other services. ie as you say, a typical “loss leader”.
I’ve been a customer of the dealership for decades, and knew the original owner when I was a kid and the dealership, like all the others, was in the same downtown block. Here’s a photo from those days circa the Fall of 1965 just after the ‘66 models were released
Z
PS
I got to ride in the Cobra sitting next to the dealership owner before it was delivered. Pretty cool for a 15 year old kid.