Personally I just don't care for taking part in one of the best pleasures in life without the downside of a hangover or getting your ear chewed. Like all of us I wish we were only paying 50 pence a litre for the essential fluid.I generally reckon to average 15. I've had it as high as 25 over a tankful whilst transitting france and down to 5 on track. It's great fun whatever I'm doing!