As investors push auto stocks higher believing autonomous drive technology will ultimately deliver a huge payoff, Fiat Chrysler CEO Sergio Marchionne is here to throw some cold water on that optimism.



"Don't believe the fluff," Marchionne told analysts when asked about self-driving cars. "I don't want to start chasing rainbows here, because if you chase rainbows you are going to fall off the cliff."



Marchionne's point: It will be a while before we see widespread use of autonomous drive vehicles and it is still too early to know which companies will succeed and which ones will fail with self-driving cars.



"The reality is that this is going to require a lot of discipline and a lot of technical know-how, which will take time. And it will take dedication and perfect execution to get to an answer," he said.



The warning came on a day when auto stocks and auto suppliers moved higher primarily due to optimism about self-driving technology.



Is there any actual indication General Motors, Ford or any of the other automakers actually know when their investments in self-driving cars will pay off? No.



For that matter, GM CEO Mary Barra said her company is still sizing up its options surrounding mobility.



"We very much believe we want to maintain a relationship with the customer," Barra told analysts. "We're exploring many options. We could partner with someone, partner with many or work on our own."



The fact is every automaker is talking with almost every tech firm or supplier about developing autonomous drive technology, ride-share platforms and ways to make money off of mobility.



It's not an exaggeration to say tens of billions of dollars have been invested. While test cars in San Francisco, Arizona, Texas and soon New York City all show how quickly self-driving vehicles are coming along, one thing is missing: a sense of how and when companies will make money off this technology.



Still, stocks like auto supplier Delphi continue to move higher. It has practically doubled in the last year due, in part, to investors believing Delphi will be a major player in autonomous drive vehicles. Tuesday, it made another big investment in that arena paying $450 million to acquire Massachusetts-based nuTonomy, which is developing autonomous drive technology.