By exemptions I meant, for eg. that, at the moment, on the NHS you can get the congestion charge of £8 refunded for coming into central london. Once the charge goes up to £25, you would be obliged to pay the full amount and yet still only get £8 refunded.
Plus, the people who drive the "chelsea tractors" will just buy another car and use that - not exactly condusive to controlling congestion in that case.
So what exactly does Ken want to do - charge for congestion or emissions or just tax people more?
I live in the extended congestion zone and it has made no difference to the traffic at all