When i am on the highway going about 55-60mph, usaually 60 but going up little hills on the highway going 55 then speeding up to 60 my whole car starts shaking and i let off the gas and it stops. By the way it's automatic, it only does it when the car shifts into overdrive going up slight hills, it's feels like that engine is misfiring or the gear is slipping, it was reallly bad before i got a new vanos unit and now it not as occurining or sometime it doesn't happen.