How Apple could make billions in the car business without ever building a car

Apple has some kind of automotive project underway called "Project Titan," and everybody assumes that the company is building a car. Probably a self-driving electric car.

But a Friday note from Piper Jaffray raises a very different and intriguing possibility.

The analysts were trying to make sense of Apple's $1 billion investment in Didi Chuxing, which is basically the Uber of China, with 90% of the ride-sharing market there.