I put this under geeky stuff as i am a self confessed tomica geek XD
I have noted many posts giving confused opinions over tomica, so i'll give all mumsnetters the basic guide to tomica and its history.
Firstly, the obvious question. 'Is thomas compatiable with tomica?' Yes, but only the trackmaster variety. Thomas the tank engine and tomica go way back to the late 80's when the japanese 'Plarail' train system had thomas and freinds added to the mix of rolling stock. the sucess was such, that the british version 'Tomy Train(s)' instantly recived the models too, to massive sucess. However, trouble brewed when the line was discontinued a couple of years later. Then in 1998, the return of the line was hailed with the 'Tomica World' Road And Rail System, where motorised trains met motorised Tomica cars (Tomica being popular 1:75 scale cars in japan). The system was innovative, ensuring maximum interaction rather than the traditional watching a train or pushing a car. Thomas and freinds recived their own 'Tomica World', which was a hot seller, causing the city tomica world line to be hastily pulled in 2004, with thomas tomica world selling till 2007. in 2007, the system changed from the japanese 'Plarail' style to a brown track, with the name becoming TrackMaster. However, desperate parents wanted the blue track back due to the brown being incompatble with the Plarail blue, so tomy sold the brand and license to fisher-price, and in 2010 brought the japanese systems of Plarail and Tomica under the Tomica name. Hope this answers the first questions, fire your questions to me and more enlightenment on the subject.will be brought soon.