Hi,
Average mpg is 28 on the manual IS200.
Reliabilty is very good, it has come top of surevy's every year. Like all cars there are some that have problems but the majority are very well behaved. I have had mine about a year and a half and not had a problem with it.
If you look in the for sale section, there are a few for in there. But what you want is a royal saphire blue IS200 sport, o funnily enough i have one for sale
Overall these are great cars and you shouldnt have many probelms.
Common faults are:
CD player error 3 problem (older models, bottom loading)
Water pump leaking
Pitting alloy wheels
Easily chipped paintwork
As long as the car is looked after then you shouldnt have many problems and they do go on forever.