1) Most recently as of now, having to replace my transmission at 91K miles. I cannot believe it, this is why I purchased a Lexus -- not to spend $5K on a $40K car in this short amount of time. I am reading all the reports of the same issue in 1999/2000 RX 300. Most disturbing is the replacement transmissions are also failing, it is clearly a bad design. I reported this to NHTSA & would recommend everyone do so. http://www-odi.nhtsa.dot.gov/
Lexus Customer Service is 800-255-3987 -- be prepared to wait a long time.
They will tell you the dealer must inspect it. They also told me they have had complaints about this particular vehicle.
My friend also told me a Lexus mechanic told him the Lexus cars have known transmission issues, and to be sure to get the major services done. The mechanic said "these are not a Toyota, we work a lot on these engines". He chose to buy an Acura instead.
2) The "blower module" went out at about 80K miles. This part blows the hot or cold air for AC or heat. Replacement part is $500.
3) The seat belts quit retracting properly. Fixed once under warranty, happening again.
4) The "light assembly module" went out. Causes either side lights or tail lights to go out -- not all of them, but the same light stays out. You can tell it's not a fuse or a light bulb because it is not in the same line, & when you change these items, it doesn't help. Common issue I'm told. $500 part + labor.
p.s. I am going to have my Lexus inspected at the dealer. If they don't do anything, I am contacting the media & starting a class action lawsuit. Very bothersome that the follow up tranny's also fail at low miles. Very poor business practice on the part of Lexus/Toyota; this should have absolutely been made right when they discovered the issue.