In my opinion no we don't need any of these codes unless totally necessary.

Do we actually benefit from having the .040 and .042 suffixes?? Plain W121 seems enough to me, with Roadster and Hardtop as added info if and when individual entries provide clear indications.

Sometimes we over-complicate codes without achieving anything useful.

I don't know if we can do or should do anything about this but ...Seems many Mercedes 190SL that appear in the pics with open or with closed soft-top have W121.042 chassis code https://www.imcdb.org/vehicles_make-Mercedes-Benz_model-W121.042.html . But this code means they are definitely the roadster version and not the W121.040 hardtop version. Which may or may not be true as their hardtop could be stored back at the person's garage W121.040 hardtops could be had with or without a soft-top as well so that complicates matters... So we don't know if these pictured were indeed the roadster or the hardtop version. And many pics are quite bad to say if open top cars have at least no retracted soft-top so these would be hardtops as well (and could we still tell?). We can only tell for those that a hardtop appears in the picture (I fixed all those). I guess a solution would be to name those just W121 but then there would be no roadsters at all... I hope my point came across as now I look back it all looks a bit confusing

Chassis code [X41] for these models
https://www.imcdb.org/search.php?resultsStyle=asList&sortBy=0&make=Dacia&model=S- olenza

I agree with you about the Wira, as it was - especially the hatchback - an interesting cocktail with Mitsubishi ingredients, but the Perodua Kelisa is just a facelifted Cuore. Seen from the rear, one could be easily mistaken for the other.

Probably yes, as we've got assorted designations which could usefully be straightened out. The post-74 facelift followed the end of the licencing agreement with BMC/Leyland UK, so Sava were able to cut loose with their own modifications, which then also spread across to parallel Pegaso-badged versions.

There are probably some Seat that should be changed though

About the Sava J4, probably because we just used Spanish origin as default. Should I already change all the pre-1974 S4?

^ hmm... I don't think it's that easy.

The Kelisa was indeed based on the Daihatsu Mira, but with a different front end (including sheet metal). I think it's different enough to remain Malaysian origin. If we were to change the origin of cars based on original designs, we would probably have to change several Seats and Ladas as well and I don't think that's a good idea.

Same goes for the Wira, the taillight design (and trunklid) is different to that of the Lancer, it's not just a pure rebadge. And if we are to redesignate model origin, may I ask that the 5-door hatchback be left as Malaysian origin as no such Japanese variation existed (a bit like that Taiwanese Charade of which name escapes me at the moment).

On a related note, I do not understand why the Sava J4 has Spanish origin. Maybe the 1974+ facelift deviates enough from the original, but the early ones are clearly nothing more than a rebadge.

Japan origin.
https://www.imcdb.org/vehicles_make-Perodua_model-Kelisa.html
https://www.imcdb.org/vehicles.php?make=Proton&model=Wira&page=1

If there is no objection I would clean the makes "Tianjin FAW Huali" & "Tianjin FAW Xiali" to use only Tianjin FAW as makes, or just "Xiali" for 1997-2008 models.
Cf https://www.imcdb.org/vehicle.php?id=1731452#Comment3282875