The basic idea is simple enough... instead of people stopping their cars (or going through drive-thrus) to get their morning food, a small springloaded cannon is used to deliver their food directly into their cars on the road.
The basic technology for launching the payload (donuts, bagels, etc) would come from the designs for pumpkin cannons. These cannons, if you are not familiar with them, seek to keep a pumpkin in one peice while projecting it as far as possible. While range is not a particular issue for this usage, the slow acceleration required to keep a pumpkin intact is a very desirable attribute.
However, given that the actual delivery is possible, there remain three major obstacles:
o Ordering/Payment
o Acquiring the target vehicle
o Reception of the payload
Fortunately, the explosion of internet technology and cellular phones makes ordering and payment almost trivial. A wide range of ordering/payment options can be imagined, everything from an internet driven menu with daily or weekly scheduled deliveries to an ability to spot order on cell phones with the charge made through the cellular provider.
Acquiring the target vehicle is much more difficult. A transponder system would almost certainly be required ... fortunately many cities are moving towards "fastpass" systems for toll roads and bridges, handily equipping vehicles with unique transponder signals. It is very desirable for this system to piggyback on these existing uses; if this can not be done, then a separate transponder must be used.
Once the target vehicle is acquired and its speed calculated, an automated launch can immediately take place.
Reception of the payload is perhaps the most difficult area. The ideal solution would be some form of elongated roof rack (elongated to leave room for windage and vehicle acceleration). Failing that, open windows and or sunroofs would have to be targetted. However, anything other than a roof rack would severely limit the total mass of the payload, for fear of harming a driver or passenger of the vehicle.