I dunno but I think you might take the prize as a highest mileage IS300 on the forum,but what do I know.'01 w/180K+. Having 2nd timing belt replaced today actually along with Water Pump, Plugs, Thermostat, Battery, PCV valve and having the fuel injection service done.
Previously had to have my hood latch system replaced (rusted out due to cracked radiator around 85K - also caused rust spot to form underneath hood lip; repaired with rust converter and DIY paint from PaintScratch.com).
We should have a sticky, with the top "10" highest IS300 out there.