I have always thought there's an inverse relationship between complexity and reliability.
The late 90's and early 2000's were dead simple compared to modern cars so there is likely less to go wrong.
Yet, at the same time Lexus (and Toyota) are cautious about introducing new technologies (Turbos, DI, etc) so mechanically I am inclined to believe they are still at the top of their game.
Rrocket will no doubt have better insight.