56K on 07, driving for about an hour yesterday everything was fine until car started surging in overdrive and the speedo is reading 10 mph when I am doing atleast 55. Then car acts as if overdrive and drive are not even engaging. I coast a little ways to a side road and slow down enough to try 3rd gear with no luck, finally 2nd works. I slow in 2nd for a little ways, slip in back into overdrive and it works. Now the speedo doesnt work, it shifts hard and shudders through the gears. No check engine light is on so I am guessing no code has been thrown. Its still under warranty, I am wondering if anyone else has had this problem and what had to be fixed? Thanks!