In my experience contracts to purchase cars are generally on a standardized form. My memory is that certain disclosures are required under either State or Federal law and I have never seen a contract that didn't clearly call out the details of what is being purchased. If your contract is anything less than that you should research this in detail as I suspect you will find it is required (not so for the deposit).
In other words the law would not obligate you to pay for the bra and I suspect the decision as to whether it needed to be removed would be yours, not the dealers (if you wanted it you could maintain that removing it would potentially cause damage and if you didn't you could maintain the car needed to be deliver, without damage as ordered).
Assuming either the contract calls out the price (which mine certainly does) of the car and what options, if any, you purchased plus a total price that would almost certainly be legally binding. Certainly it would be binding if the dealer voluntarily put some option on and then attempted to tell you you had to pay for it. However it is possible that the contract provides for a pass through of a price increase under certain conditions. But if that was not specifically included then I would think the contract would be binding at the prices listed.
As manufacturers love to remind us dealers are NOT agents of the manufacturer. They are independent business that purchase cars and resell them. So whatever the contract says is generally binding, except to the extend that if violates some law.
So read your contract very, very carefully (preferably next time before you sign it). If you believe it is clear that you agreed to purchase the car at a set price and there is no pass through clause or the equivalent I would simply transfer good funds (preferably by wire directly to the dealers bank account) and show up to pick up the car. If they refused to give you the Certificate of Origin you could allege breach of contract and demand damages or even go for a restraining order preventing them from selling the car and demand specific performance (money isn't good enough you want the car).
They could of course simply refuse to deliver it but I suspect if you are on solid ground in how you interpreted the sales contract they would be concerned (rightfully) about punative damages and would quickly cave.
Because there have been scams involving just these sort of add ons in the industry the laws tend to be very pro-consumer. Frankly I am surprised that Lotus would permit such a thing. Since these cars are built to order they might have liability if they knowingly accepted an order for a vehicle and added and required payment for unordered options. Such behavior would certainly be civil and might even amount to criminal fraud.
Is this just conjecture or are you aware of this actually going on?
