You seem pretty knowledgeable about the topic itself... anyway,
here's my 2 cents on this issue :-
1) Check out all the cars of the same model to get a feel of the
'market' price
2) Call up dealer and say you are driving xxx model and ask roughly
how much they 'eat' this car, to get a gauge of the resale value to
dealer
3) Check the PQP COE price (LTA or onemotoring etc) of the date the
car was renewed, to get the actual paper value of the car
Always assume that COE cars have no body value in the case of a
total loss or self-accident, and that you will only get back the
COE rebate.
As for driving it for awhile then reselling, see point 2, and also
depends on demand, COE prices, car condition etc... at the point of
your sale.
Basically, when you buy a COE car, you are paying premium $ that
finance companies and insurance companies DO NOT FULLY RECOGNISE.
In their eyes, your COE car is basically just the paper value +
maybe a bit of nominal sum.