Hi Jeremy
We have a 6 speed manual 2000 model IS200 which gives 8.3l/100km on a highway trip and 10.2l/100km on town running. We always expect at least 600+kms before refilling. Have learnt that premium grade fuel 95octane plus gives cheapest running. Works out at about $2 per 1000kms cheaper than running normal unleaded. Not much but you get a better running motor and some extra power - which the IS200 could do with.
ciao