Does anyone know whether provisions have been made to mount a rooftop bicycle rack on the Model S?
You can undoubtedly add a roof rack for bikes (or anything else you care to put up there) but remember that this car has been designed for minimum drag = maximum range. Adding any racks and extraneous elements will reduce range. On a car of this calibre, I would be hard-pressed to add a rack of any kind - it is a luxury car, not a mini van or SUV.
Using only SUVs and pickups to transport bikes, tow trailers etc. is an american thing. In Europe, you'll frequently see for example BMW 5-series cars towing big camper vans or trailers (up to 4500lbs), having bikes or skis on the roof rack etc. We don't keep a second car around for the few times we need to tow or use the roof rack, many families have only the one car and it need to fill all our needs.
Nice thing about the Model S: Depending on the number of passengers you plan to take along, and on the kind of bike you are talking about, you may be able to carry one or even two bikes inside. :-)
I am not yet convinced that there will be any rack mounts on the roof, but I sure hope so. Alternatively, a trailer hitch may be a viable option for a bike rack: It is far more convenient because you do not have to lift the bikes up high, and the drag coefficient will not suffer as badly as with a roof-mounted rack. But I am not sure if a hitch is planned as an option, either. I think both questions are mentioned somewhere in the Q&A thread and I still hope we may get some kind of answer soon:
Rumor has it that prices for options will be announced "this summer" (yes, 2011) so some of these questions may be answered by the soon-to-be-published options list.
At the prototype tour stop in Toronto the rep mentioned that you would need to get the sunroof to get the connection points for the roof rack. I didn't probe any further as to why that was the case but wanted to put it out there as something to ask when you get closer to option selection.
My preference is to put the bikes on the rear hitch mount as they are way easier to access and aren't in the wind as much.
That would be my preference as well. I don't want to tow anything, but a bike carrier that mounts on a hitch mount would be ideal.
Add me to the list of those who prefer a hitch for carrying bikes instead of roof racks