With the Michigan manufacturer plates on the SRT it's probably a test mule. Last May I went down to Toronto to work at my old limo company for 4 days cause they had a order from DMC for Mercedes execs wordwide. They sent 6 Hemi Chargers and 2 SRT 300's. They all had those plates on them and between 5000 and 10000 miles on them. Also 21 brand new S series Mercedes. All my boss had to do was provide drivers. The Chargers and the SRT's were not put on sale till later that year.......Oh, I got stuck in a S600 AMG for 4 days, but did get to smoke the tires on the other 2 around the office.