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.

They make a very good point: Customers of ride-sharing companies don't particularly care what kind of car they're riding in. They just want to press a button and have a ride show up to get them from point A to point B.

So maybe Apple isn't interested in building a car at all. Maybe it's got grander ambitions to power the future of transportation.

As Piper Jaffray puts it:

When consumers use an Uber-like service, we believe that brand of the vehicle is of little concern ... We believe that being the taxi service platform is likely to be the most lucrative part of the business vs the hardware (car) side of the business. While it is difficult to determine the full intention of Apple's investment, if the company were to integrate the software elements of an autonomous taxi service with stylishly designed and easy to use hardware in cars, perhaps Apple could replicate the integrated hardware/software model that helped make the iPhone so successful.

So what does that mean?

Imagine pressing a button on your iPhone or Apple Watch, and a car with no driver pulls up. You get inside and tell Siri where you're heading. You ask it what traffic's going to be like on the way. You tell it to tune the radio to the game you're missing, or to use Bluetooth to stream a song you want to hear from your iPhone.

Then you sit back and work or play on your phone, tablet, or laptop, connecting to the internet over the car's built-in wireless connection.

The whole thing is powered by Apple hardware and software, but it's not exactly an "Apple car." It's part of a bigger transportation experience. Call it iCar. And investing in the biggest taxi service in China could be a great way for Apple to start collecting data to help build that service — and eventually give it a proving ground to launch it.

It's actually easier to imagine that Google has something like this in mind, too — it's got the services in place (particularly maps) to power that kind of service, and it's already partnering with car companies like Ford rather than ramping up production on its own cars.

Same with Uber itself — just because it hired a bunch of researchers into self-driving cars doesn't mean it actually plans to build these cars itself.

These are software companies. Not car companies. Maybe that's how the real disruption to transportation will happen.