I did a trip Karur-salem- Chennai-Salem-Karur and got the following figures with my Fiat Punto mjd 90hp. Passengers : 4 adults and my 6 year old daughter with good amount of luggage. 95% Highway, 75% AC on, Maintained speeds between 90 and 110 kph barring the usual heavy traffic between chengleput and Chennai (both during onward and during return). The 5% was within Chennai city in Bumper to Bumper traffic for ~25 Kms (A Test drive(!?) by my Brother-in-Law) and ~15 Kms in Karur city.