mercedes 230ce, silver, 1991, well below average mileage (verifiable),
2-door coupe - the one with no centre pillar i.e. when all windows
down, there's just one big uninterrupted 'hole'. tax & mot 6 months.
excellent condition, no rust. petrol, automatic shift, power windows
all round, aircon

local trader tells me basic 4-door non-coupe average mileage instances
of these are not so valuable, but this one may have a higher value due
the above.

This vehicle does not seem to appear in the car trade industry
publication 'parkers guide', the standard guide to second hand car
pricing.

Can a researcher provide a rough ballpark idea of the likely private
sale value of this car, and what would be a reasonable figure for
trade-in?