I jumped through all the hoops and got my C1 and E licence a couple of months ago. (Many, many hoops to jump through, but that's another story.)
I ride a gasoline-fired "Da Gui Wang" (the cute, vaguely Aprilia Havana-styled ripoff made by Geely) whose compliance plates and papers show that it has a 49.6cc engine. But in fact it's a 125cc. I purchased it new in Shanghai a little over a year ago and I have the original fa piao and papers.
According to this very thread, and other websites I have perused, a 49.6cc bike needs a blue plate, but a 125cc needs a yellow plate. So the appropriate plate for this bike would depend on whether one believes the compliance plate and papers, or inspects the engine directly. I suspect the former carries more weight.
Compsolutions' post from March 09 states that "no more gas powered bike licences are being issued". However, Article 12 of the Shanghai motorbike law states: "Permanent residents in all the counties, as well as in Pudong New Area (areas beyond the Inner Ring Road), Baoshan District, Jiading District and Minhang District may apply for a suburban plate." So compsolutions' statement presumably applies only to the area within the inner ring road. Unfortunately, that's where I live.
I could just continue to ride my scooter without registration or plates, or alternatively use fake plates, but I'm worried about not carrying third-party insurance. What if I'm in an accident and someone is injured?
It occurred to me that I could register it as a 49cc gas bike with blue plates, under my GF's name (she lives in Baoshan but has a Hunan ID card - nevertheless she does have some kind of residency permit for Baoshan), and this way I could get 3rd party for the bike.
The bottom line here is we must lower our cost base to make room for a lower margin product mix world and to grow our earnings going forward.