Thanks to a message from a passing bird, I have heard that SEGA is considering Hatsune Miku as a downloadable content character for “Sonic & Sega All-Stars Racing Transformed”. The idea is in its first voting stage on the SEGA message boards, and the thread can be found here: *Link removed, fist stage voting has ended*
Hatsune Miku, among many other game characters from SEGA are listed as choices. The list is not limited to these choices, and you can also pick non-listed characters as long as they were in a game developed by SEGA.
To cast your vote, you need to register an account and vote for three characters. Failure to follow this guideline will result in your vote being nullified. They are also finding it odd that there are many new accounts being created to vote for Miku. So be sure to say where you heard the news from, whether it be this blog, facebook, twitter, or some other site.
Voting ends November 19th.