I have had my IS200 from new in 2001 (Y) - 56K miles. It is still on its original battery. Starts first time except when it didn't move for 2 weeks during our arctic spell. The battery was completely flat. Since then it has been fine with volt guage reading 13V whilst driving. Am I living dangerously and should I replace it before it embarrases me. No intention of selling soon.

i reckon it should be fine mate. i would replace it when it takes time to start up