what is the best way to lessen fuel consumption for 2006 renault clio classic

Keep your vehicle maintained..tuneups..etc. and keeping your tire pressure at the maximum recommended level. Also.drive normal.No jack rabbit starts..rapid braking.constant speed while driving.etc

Not speeding or trying to race it would help (let the idiots who think everything past a traffic light is a drag race strip get ahead so they kill themselves without running into you) as would anticipating traffic so that u do not have to speed back up as much. Use the highest gear u can (or if you've got a car that coddles the driver too much put the transmission in economy mode).

Keeping ur tyres inflated & excess junk out of ur car will help as will closing the windows (using the air conditioner is more comfortable & uses less fuel than opening the windows).

Servicing ur car according to the manufactures recommendations is something u should be doing (although u wo not be getting a tune up, modern cars do not need tune ups since the timing on computer controlled engines does not go out of whack & need readjustment) but fluids & things like spark plugs still need changing (and if there is a problem with ur car u probably want it fixed).

After market products that claim to increase fuel economy usually do not work so do not waste ur money on them.