Since the second quarter of 2013, Tesla's adjusted revenue figure has exceeded revenue figures based on Generally Accepted Accounting Principles, or GAAP. The blue area is revenue that comes from vehicle leases backed by a resale value guarantee. Tesla expects to recover a certain amount on the sale of future post-lease vehicles to pay back banks that "buy" the value of the lease that the company books as income. The risk factor is whether Tesla is overestimating the future resale value of the post-lease cars that are returned to it after 36 or 39 months. The black line is what the U.S. Securities and Exchange Commission requires Tesla to report. The blue line is CEO Elon Musk's preferred measure.