>>Back then cooperation between different car makers was MUCH less than the level seen today. An approach preselecting the sub-set to be searched by make and model might throw casual users off if you consider some nearly monozygotic twins found today.
>>Just contemplate Toyota GT86 and Subaru BRZ
>
>In those cases, the make would be Toyota and Subaru, and the model would be GT86 and BRZ, exact?

Depending on the actual make entered, the "other" car would still be shown up very high in a final selection list of sports cars of the make picked, allowing a face/palm accompanied correction.

The mathmatical model used to estimate residual value would be somewhat weighed more to the make it was sold as - as some factors like quality of maintainance are slightly higher correlated to make (from "typical" customer willingness for maintainance and workshop/garage quality found in specific country).