Dude it's just driving sensibly and keeping your car in shape, having said that you'd be surprised how bad some people drive in relation to efficiency and have a severe lack of common sense. Also depends totally on the type of journeys you make. Unless you do mega miles a year just enjoy the drive otherwise you'll only save a few pounds.
Love the suggestion of removing golf clubs, tool boxes and prams / push chairs. What if you are your way to the Golf club and was dropping your child off at the inlaws and you was lending them your tools.
Just common sense, so unless you drive around like Jeremy GTI with 4 bags of sand in the boot, and have under inflated tyres then read on.