Thanks for telling us about your session, Robert. Your big shouting letters at the end show you are passionate about Clean! Your account seems to me a good example of how coming from a Clean philosophy and using Clean-ish questions can be very effective in helping a client to self-model.
Picking up on your point about a car always being in some sort of 'condition', this kind of awareness has been referred to before (by James Lawley I think) as 'working within the inherent logic of the metaphor'.
Other examples of the inherent logic of a Ferrari metaphor might be a car body, driving, paint job, exhaust sound, steering wheel, seats, CO emissions, wheels, etc. Things which help to define it as a Ferrari .
However, remembering that we are in a constructed, virtual world when we work with metaphor, sometimes a person's metaphorical car is not like a real car. Their particular metaphorical car may fly, be made of sugar, talk, eat daisies - anything at all. Yes, usually a metaphorical car is like a real car but it's worth not getting too convinced by our own assumptions.
Note that IMO asking 'Who is in the car?' when the person has not mentioned occupants would not be working within the inherent logic because having occupants does not define it as a car. A car is still a car, even if no-one is in it. Yes, a car is still potentially a car if someone has stolen the wheels, however it can't perform the functions of a car until it gets some wheels again. So perhaps a way to define factors that are in the inherent logic of a metaphor are those that if you took them away the metaphor would cease to exist.
I wonder what would have happened if your questions had been cleaner? For example instead of 'What condition is it in?", simply asking "Anything else about THAT Ferrari F40?" a few times might have got condition information AND something else (e.g. "it's essentially a good, solid car, it's very quick but it's in poor condition").
To my mind, the issue with introducing words from our own map into the client's map is not that it in some way might injure the client but that it limits their attention at a time when there might be more learning acquired from broadening it. Also it trains their attention on something WE are interested in rather than on what may be foremost for THEM. We could end up missing something that they don't mention because the questions limit their responses.
For all these theoretical distinctions, it sounds like your client got plenty out of your interventions.
Phil