Autonomous cars haven't existed for a while so I'm a bit skeptical Apple will be able to deliver something trustworthy.
There's no reason they can't be working on a car that won't be released for 5+ years, after the market has matured.
Granted, earlier this year we saw them meet with Apple-centric press to tell them "don't worry, we're building another Mac Pro, just not in 2017", but those present pointed out how un-Apple-like it was to make such an announcement.
If Tim Cook unveiled the new car today, som62345's concern would be valid.
For now, we just know it is an area of interest for Apple and they may one day release a product.
Perhaps the more interesting part of this is that this is the the second time since Steve Job's death that Apple has revealed an area that is working in before unveiling the product.