After careful consideration between another Mercedes S-Class, an Infiniti Q45, and the LS 430, I chose Lexus. Never having owned one, and with all the hype about the brand's quality and service record, I found it to be the best choice. I was very pleased with my initial period of ownership. The performance was great for the MPG I averaged around town (compared to my 03 S500). The trade-off in power didn't disappoint. The cost of maintenance was also dramatically lower than the Benz. The vehicle has been mechanically sound so far and I credit that to Toyota's years of powertrain technology innovations. The only part that is lacking on this car is, in my opinion, a sub-par interior build quality.
Climate-controlled seats, very efficient A/C.
Better interior components such as switch panels that are shared with Toyota Avalons and others, brighter HID headlamps. A little more HP couldn't hurt either.