J
jay
This may be suitable from schluter and would be available special order from your CTD http://www.schluter.com/1_2_reno_ramp.aspxou
However before you order it check that they agree it would be suited to have the weight of a car going over it daily.
I agree that from an expansion point of view the slab shouldn't need expansion joints running through the field of tiles but I would leave 4-5mm expansion at all the edges where tiles meet the walls and fill with Silicon to allow for potential lateral movement from the forward motion of the car pulling away.
have to agree with that a bit of a concern