I have a 2006 300C and a few weeks after we got it, with only 1,500 miles on it....it was late at night and we were 25 miles from home. I hit the gas and the car just coasted. It just sounded like the engine was revving. Finally it clicked into gear and wouldn't go above 2nd gear or about 25MPH. All the lights lit up on the dashboard. Of course nobody at the dealership so we drove home in the slow lane on the freeway going 25. We must have looked stupid to everyone with this hemi engine going 25. Anyway, took it in to the dealer and they told me (and my husband) that there was water in the transmission. Their explanation of it was that some Yahoo on the assembly line ran the A/C condenser hose into the tranny. Everytime we turned on the A/C, water was trickling into the tranny. Don't know if that is the truth or not, but the dealership REPLACED it. I told them i wouldn't accept a rebuilt one and that it had to be new. after some haggling, they agreed to do it. it has been ok since, but we don't put many miles on it. had it now for 5 years and have 40k on it. NOTE: i was also told that the reason the car dropped down to 25MPG was the computer. if it senses a problem, it gives you minimum power as to not make the problem worse so you can get help.
I did have another problem last year. I was parked head first in a parking space at church and when i went the backup, the car wouldn't go in reverse. The gear shifter wouldn't move. tried the first trick of disassembling cover to over ride and that didn't work. only after i was told about another over ride on it, could i get it going. i managed to get home and then they towed it. it was still under warranty so it didn't cost anything. but i feel that people should know so if they have the same problem, they don't feel they are the only on.e