:Offtopic:
Agreed, the 1.6 naturally aspirated Suzuki engine is very smooth and I believe economy is directly related to the use of 0w20 oil which manufacturers are now turning to. Problem is, 0w20 oil is very expensive compared to 5w30/40 etc. Average price of 0w20 oil appears to be around £12 + per litre
Castrol Professional is the recommended oil for the Vitara but just as with the TwinAir and the (imo) high cost of Selenia, you have to decide whether to stick with the manufacturer recommend lubricant, or substitute it for something cheaper if you can find it. At the moment, I can only find one other 0w20 oil which meets the correct specifications, but as i'll be sticking the car into a Suzuki dealership for service next year, it'll get whatever they use, and I'm assuming it will be Castrol Professional.