Purchasing a vehicle is cleaner without a trade in (tesla or otherwise). Even if you are trading in a vehicle, most advice would tell you to separate the transactions in your mind, because selling a vehicle and buying one are two different transactions.
At a traditional dealer, it is very common for them to give a higher price on a trade in, especially if they think they are selling you a car, because one of the fastest ways to upset someone in a car deal is to offer them a low price on their trade in. If a dealer is selling you a car and taking your trade in back, they will generally give you a higher price on the trade in, and then try to take it back out of the new car.
Said another way, at a traditional dealer, if you get top dollar for your trade in and are buying a car from them, you probably left money in the new car side of the deal. Separating them is better because dealers do those deals all day, and also plan on finance credits, etc.
Tesla doesnt do any of that, and just sends the car to auction (they are taking the trade in for convenience in other words) so its better to separate out the selling of the car from the buying of it, if you can and it makes sense. In this case it sounds like it makes sense, so if (AND THIS IS A BIG IIIIIFFFFFFF) you can sell the car and do without it while you wait for the Tesla deal to be finalized, even if there are a couple of delays, then do that.
If you cant ("I only have this car and need to get to work, and dont want to rent a car / take public transportation" ) consider that into the mix. Also, where I am (CA) does not give tax credit on trade in, so I always ignore that, but lots of states do, so if yours does, you need to account for that as well. If your state does, then you may see the deal is closer while trading into tesla than you think.. unless you are going to put the deal on hold for longer than Tesla is going to hold the price offer on trade in.
