Alignment / Ride / Tracking Issues

[VolantLexus]

I recently purchased a 2010 GS450h with 13 miles. The first time I took it onto the highway I noticed the car meandered within the lane. At 55 it was not noticeable, at 65 it became noticeable, at 75 it was even more pronounced -- and at 85 it was downright dangerous... It took a lot of steering wheel adjustments to maintain lane control and every little road irregularity sort of pushed the car in a new direction.

I checked the tire pressure (35lbs all round) then took it to the dealer to have them check it out. They added more toe-in which did reduce the problem, but it is still there. The car simply does not track in a straight line. It doesn't pull in any one direction, but it does like to wander left and right.

The dealer states it drives the same as like models.

I'd like to verify that. Do other GS450h owners experience this effect when driving on the highway?