The company guarantees that all orders placed by October 15th will be delivered by the end of the year. You'll have to take delivery -- that is, pay your balance in full "either personally or by way of guarantee from a financing institution" -- by December 31st, 2018, but you will get the full incentive. If you put off your purchase or don't take delivery until next year, though, you can say goodbye to that $7,500 in savings.

Purchases delivered from January 1st to June 30th, 2019 will only get a $3,750 credit, while those delivered from July 1st to December 31st, 2019 will only get $1,875. After that, Tesla will no longer be able to offer tax incentives. In case you were waiting for the $35,000 Model 3 and were hoping to buy it for $7,500 less, consider that dream canceled.

The law could change in the future, though that may or may not be a good thing, depending on whose proposal passes. Vermont Democratic representative Peter Welch wants to eliminate the 200,000 ceiling and instead give EV makers a 10-year limit. Wyoming Republican Senator John Barasso, however, wants to kill the incentive and impose a federal highway usage fee for vehicles using alternative fuel. "There is now a stable and sustainable electric vehicle market in the United States so I think taxpayers ought to be off the hook," he said.