Parthiban and Kam, Yes the IS200 is not exactly the most fuel economic car, but i'm sure with some tweaks I can get more out of the fuel without affecting comfort or performance... The basics would be correct or even over inflated tyres, and as Parthiban mentioned easing air intake etc.
If this stupid government cared about the environment so much, it would stop putting speed bumps every 10 metres... accelerate, stop, accelerate, stop,... fuel killer.
Anyway, if i come across something worthwhile, i'll add it here. Thanks guys.