So I pulled over today before getting on the high way and threw my transmission into overdrive. I got on the turnpike and noticed that the rpms were higher than they are in normal drive, what's up with this? I noticed it wouldn't shift gears it sped up to 70 mph on the same gear, or maybe I didn't notice the shift, but at 70mph I was at 3500 rpm where I'd be on 2500 on regular drive.