Hi,
It's been about 5 years since I posted my original comment... ;)
My GSH450h is still going strong after more than 120,000km.
My batteries are fine - never had any problems with it or anything else on the vehicle - gotta love Lexus quality.
My fuel economy is practically the same as it was when it was new in 2007 - I still get 700km tank average.
It was only very recently that I managed to have the time to make some mods to my car, specifically around the Navigation Lock override and DVD lockout as well as introduce an after market ipod and Hard Disk integration
I also installed my own bypass switch for the Nav lock and DVD lock override purpose - if you are interested and you would like me to help you do this change to the car, do let me know.
Regs,