It certainly seems overvalued, even with the debt paydown. (New equity really helped).
I back out long-term units of 20m a year to justify the valuation. They are going to have to develop many more models as most leading car models seem to top out at 1m in units. But we will see.
Aside from the valuation, I don't like the percentage of sales that come from energy credits. The government can change this reimbursement and as competitors ramp and mileage improves, there won't be the need for as many of these credits. Their competitors will stop buying them.
And of course, there are the macro issues-lithium, power grids, power capacity, etc., all of which might become more scarce and expensive in the face of a huge shift in share.
They have done a great job getting operating margins into the 20s and gross margins into the 30s-due to a nice ramp in Shanghai. The problem here is that if credits are 1/4 of their sales, these are 100% margin sales that are at risk.
There is also a question aside from environmental credits when it comes to margins: TSLA doesn't amortize warranty expenses like other car makers.