hi, have recently purchased a 2011 odyssey. there is a significent vibration
felt in steering wheel and seat. dealer claims is normal. honda america defers to dealer. this occurs in or out of eco boost. at all speeds but particularly at speeds 38 to 42 and 70 to 72 mph.

 

Have you looked at the motor mounts? It's not uncommon for them to go bad.

 

Check tie rod ends. Sounds like youve got a worm one. This is the step before death wobble in the jeep world.