Depends on the model of the ipad whether or not is automatically on there. Also it will only be found if there is a WIFI (unless it has it's own data card). or the bloke has stolen it and it is on a network. Another option for you could be to ring your insurance, and see if the theft would be covered, but your excess is probably same/more than ipad value. But I have a special cover for this type of thing. If it is new model ipad they will have trouble getting into it, as you need all the passwords for your apple id etc to reset it etc.
Also as precaution, I would double check your car, and under seats incase you didn't zip up the backpack and it has fallen out of the bag, into your car somewhere ?
Hugs, that really sucks