Putting too much info is not always a good thing.
There are comments for thing like range year. I am not sure that it would be useful to have also an end date. I could add it, that's not a big problem. I already did it for movies entries, since series need an end date in addition of a start date.
Model type or series number can be put in what is currently called "Chassis code". For Cadillacs we were not using it, but we could do that.
Model/series name goes to model name field.
Then we miss the sub-make and sub-model as you described it. I could add such fields, but would they really add something compared to the current solution, where these two info are put as "extra info"?
For the body style, it is currently selected from a list. If it was as a free text, it would have two problems:
- translation in French (and in German if people use it), or in English in the case of French cars. What about the name of cars in other languages then, if we take the body type given from the maker and not a standard type from a list?
Additional comments can be put in "extra info" field, but also in the... comments. At first these were added for that, for allowing people to give some info about the cars, not only for discussions

Antoine, is there any way you could prepare a "table" with appropriate headings and sub-headings that contributors need only fill in "boxes" with the basic info: (a) model year [even if built earlier or later], or range of years [if unsure], (b) make [e.g. Austin, Bentley, Citroen, DeSoto], (c) model, type or series number [e.g. "T", "55", "V-63", etc.], (d) model, type or series name [e.g. "Somerset", "Continental", "Kingsway" etc.], (e) sub-make [for custom coach work - e.g. Chapron, Darrin, Figoni & Falaschi, Fisher, etc.], sub-make name or number [as appropriate], (f) body style [e.g. sedan, coupe, convertible, town car, etc.] and (g) additional interesting comments about the particular vehicle. I think the present identification criteria are inadequate for many movie cars that I have seen on the site. It's a GREAT site but there is always room for improvement.

I was thinking of indicating unsureness in the comments rather than for posting.

If the one posting is unsure then they should just put unknown or leave blank.

I see too many affirmative comments that are wrong and think we need some easy and consistent way to indicate a degree of doubt.

A problem linked to that: if most of the time people have to indicate that they are not sure, then we would not rename the vehicle until it is confirmed. This would force to confirm lots of info posted And for things like years (empty year field does not make the car appear as unknown), there may be vehicles missing a year only because the one that posted the info was not 100% sure, though we could have used that info.

Might be handy to suggest question marks. none = 100%, one = almost sure, two or more is best guess.

I'll add a note about that above the posting area
But if somebody is sure about an auto, even if he is wrong... how can we solve that?

I notice that a number of contributors are identifying cars wrongly (I am referring only to Cadillac models here, since that is my speciality). Please, "antp", would you kindly invite all who claim to have identified a movie car, to state if they are (1) 100% sure or (2) almost sure or (3) just making an educated guess. IMHO, this site must tend towards 100% accuracy or we are all wasting our time. Thanks.