2007 460L rides rough

[Liberty Man Van]

I just bought a 2007 LS460L from a dealer in Lexington, KY, USA.  It has 83,000 miles on it.  I didn't notice it during the test drive but on the drive home on the interstate highway I noticed the car did not absorb shocks well.  At slower speeds I can slightly hear something rattling underneath when going over a bump.  The ride seems much rougher than I would expect from this vehicle and I seem to feel every small undulation in the highway.  The rear end seems to rock up and down after traveling over a hump.  It has the adjustable suspension with the sport or comfort option.  Switching to the comfort option doesn't seem to improve the ride.  The handling part seems to be ok.  It does have sport tires on it but I am skeptical they make THAT much difference in the ride.  The ride reminds me of the old corvette my wife was driving when I met her; beautiful but not smooth!  Has anyone had similar issues?  Any experiences or recommendations are appreciated.  How to find a shop that KNOWS suspensions and not the truck lifting kind?  I paid for a Lexus and got a conestoga wagon!

[Lexus Owners Club]

Hi....welcome to the Club

That doesn't sound good as the ride should be smooth and no noises should emanate from the underside of the vehicle.
I would highly recommend that you take it to an independent garage for them to check it over thoroughly before committing to a purchase.
It could save you a fortune and if they are not keen on this occurring then I would imagine there is a good (but not genuine) reason for this.