London's daily congestion charge rises from £8 to £10 from Tuesday.
The zone's western extension was removed by Mayor Boris Johnson on 24 December after a public consultation. He promised in his election manifesto to listen to Londoners' views.
It means drivers will no longer have to pay on streets west of Edgware Road, Park Lane and Vauxhall Bridge Road.
The charge in central London can be cut to £9 a day by registering for a new automated payment service.
This will record the number of days when a vehicle enters the zone and then charge the owner's debit or credit card on a monthly basis.
Anyone who leaves it until the day after travelling to pay the fee will face a £12 charge, compared with £10 in 2010.
Zone 'never justified'
The changes to the boundaries mean the scheme reverts to roughly the same area as it covered before the western extension was introduced in 2007.
Cameras which recognise number plates are used to detect all vehicles entering the zone between 0700 and 1800 GMT on weekdays.
Among those pressing for the western extension to be scrapped had been the West London Residents' Association, which could not understand why the charge applied to anywhere other than central London.
"The imposition of this tax was never justified," said spokesman Gordon Taylor last month.
But the Campaign for Clean Air warned of greater pollution when vehicles were once again able to access west London for free.
And Labour's candidate for London mayor, Ken Livingstone, who introduced the western extension, said there was "no financial sense" in cutting the zone and losing £50m in revenue at a time of widespread cuts.