That is not how it works. I suggest you read the posts about margin, COGS, ASP etc in the finance thread.
COGS is the cost determined (one of the ways, anyway) at the time of manufacture. They take the cost (avg, FIFO etc) of all the parts that went into that car, labor allocated to that car, depreciation allocated to that car etc. Usually this is done by model, trim, options, rather than individual car in practice.
But margin is determined at the time of sale. Margin = (Sale price - COGS)/Sale Price. This is also usually determined by model+trim, but reported only at Tesla level.
So, a particular car comes with a particular COGS, attached to it in the quarter it was manufactured. But the price and the margin is determined only after the actual sale takes place.
Given a particular COGS, you get lower margin if the price (or ASP) is lower. The kind of ASP you are estimating (which I hope is too low) would give very low margin. I didn't look into why you think ASP would be that low, though.
COGS = 80K
ASP1 = 100k , Margin = 20%
ASP2 = 90k, Margin = 11%
ASP3 = 80k, Margin = 0%