We've known since last week that Apple was working on some sort of car-related project. The big question was whether Apple was working on a line of car accessories — perhaps expanding on its existing CarPlay platform — or whether the company was going to start building its own cars.

New reporting from 9to5Mac provides strong evidence that Apple is working on an Apple Car.

Cars are complicated, and building one requires skills that a high-tech company like Apple doesn't normally have. According to 9to5Mac, Apple has been snapping up engineers with expertise in motors, transmissions, drive trains, car interiors, and so forth.

The list includes four people with experience at Ford, four who previously worked at Tesla, a former CEO of Mercedes-Benz, and a General Motors employee. Apple has also hired an engineer from auto-part maker EMCO Gears and multiple engineers from A123 Systems, which makes batteries for hybrid and electric cars (A123 has sued Apple over these hires).

It's unlikely that Apple would hire people like this if it were only working on car accessories. And it wouldn't hire hundreds of people just to work on a pilot project. Granted, Apple CEO Tim Cook could still decide to cancel it if the results aren't up to Apple's standards. But there's a good chance we'll see some kind of Apple Car in the next few years.

Apple is well-positioned to create a new kind of car

Apple may be better positioned to jump into the car business than almost any other Silicon Valley company. Most tech companies focus on one relatively narrow piece of the technology "stack." You've got Intel and AMD making computer chips, Dell and Samsung building devices, Google and Microsoft developing software, and so forth.

Apple is virtually alone in building its own products from top to bottom. An iPhone is based on an Apple-designed chip and runs Apple-designed software. This philosophy makes Apple particularly good at re-inventing product categories, as it did with the iPod, iPhone, and iPad. It can build exactly the right hardware to support its software, and vice versa, creating a seamless user experience.

This kind of tight integration between hardware and software will be particularly important for cars, where reliability and energy-efficiency are major priorities. Apple's work on iPhones, iPads, and MacBooks also means the company has experience with batteries and power management, which are also crucial to building electric cars.

Indeed, this could be a weakness for Google, which has traditionally created software that runs on other peoples devices. Combining Google's self-driving software with a conventional car might produce a less appealing product than having one company design the whole product

It won't be easy for Apple to catch up to Google on self-driving technology

By the time Apple brings a car to market, partially self-driving cars will be commonplace and fully autonomous vehicles may be right around the corner. To compete with Google, it will have to build its own self-driving technology. And that won't be easy.

Google has a five-year head start creating self-driving cars. It also has a fleet of Street View cars that will allow it to produce detailed 3D maps of the world's streets, which will be essential to helping self-driving cars stay on the road. Apple doesn't have a great track record with maps — Apple has struggled to produce a mapping app that rivals Google Maps.

Google also has a culture that prizes tackling difficult engineering problems — dubbed "moon shots" — like building a self-driving car. In contrast, Apple has traditionally been focused on building beautiful, user-friendly gadgets. When it has tried to expand outside of that core area — as with iCloud and its predecessors — the results have often been disappointing.

On the other hand, building a beautiful, reliable, and energy-efficient electric car would be a major feat in its own right. Even if Apple struggles to catch up on the self-driving front, it could still sell a lot of conventional vehicles before autonomous vehicles become ubiquitous.

Disclosure: My brother is an executive at Google.