The right kind of perspective on this is -- and it will make some people apoplectic -- future cars are like iPads with wheels. They both are basically giant batteries with very sophisticated software and well crafted interfaces. Apple has the engineering organization to deliver those key things along with a certain approach to integrating services, sales and support. What they're missing is the automotive engineering and that's something Tesla has done a great job of building up.
The price would be unusually high for an Apple acquisition but only in absolute terms. What makes it an "Apple-y" acquisition target is that it's an engineering piece of a much larger system, the "iPad on wheels", where the real future value is.
That is why Jobs was confident an Apple car would take 50% of the market. Not by building a better mousetrap but by redefining the product category.