Unlocked car doors and discarded cigarette butts could leave smokers and motorists lighter in the pocket thanks to tough new fines to be enforced from today.

Police will fine motorists in the Yarra Ranges up to $358 for leaving their car doors unlocked or windows down.

Meanwhile, roaming inspectors are on patrol in Melbourne enforcing fines up to $234 for unbinned butts.

From today, smokers face a $234 on-the-spot fine for throwing away a burning cigarette and $117 for littering an extinguished butt.

Melbourne Lord Mayor Robert Doyle said cigarette butts were the city’s biggest source of litter, with up to 11,000 cleaned off the streets each day.