London congestion charge increase for older vehicles
The London congestion charge was introduced in 2003. The charge works as a discouragement to motorists to drive into London in a car that causes pollution.
There are some vehicles that are exempt from the charge, such as the Audi A3 e-tron BMW i3 and Renault Zoe, as well as others.
Things are due to change though. Older vehicles not meeting the Euro 4 / iv emissions standards (euro 3 for a motorised tricycle or quadricycle) are due to be charged an extra £10 per day from 23rd October 2017.
If your vehicle falls in this bracket, it may be worth considering your options.