The historic transformation of the automobile industry will generate billions to trillions of dollars for companies and investors. But for traditional automakers, the road ahead will be bumpy, risky and expensive.

That’s the assessment of consulting firm AlixPartners, which released an extensive report Wednesday that uses market research and consumer surveys to lay out some of the major challenges facing automakers — with some interesting findings about Tesla. The report includes a near-term industry outlook with a darker forecast for U.S. auto sales than most other prognosticators have put forth.