For many of these cards, we'll have an exact match by XP in the market, but sometimes the market does not have a card with the same XP so it's hard to judge value. In this case, I've looked at the market and found the value of the 'next lowest XP' in the market. In this case, we see the second card says, '120 card XP, 100 market XP' and if you click that you'll go straight to the market to see the value of cards at that XP. The idea here is to get the value of the card that is closest to yours.

This is very bad idea :) It should be done my looking at value of single card and multiply by BCX of given car.

VS