However, as ever, the best laid plans have gone awry. In anticipation of the new rules Britons began snapping up low CO2 vehicles in hopes of avoiding the charges. Sales reportedly jumped by over one-third through the first three quarters of 2007. Now Transport for London is considering abandoning the changes over concerns it may lead to increased congestion and lower revenues. If they do this a lot of people who bought these vehicles solely for this reason would be awfully upset. The Mayor needs to decide what his real goal is. If it's reducing congestion than keeping a flat rate on all vehicles is the way to go. Congestion has nothing to do with how much CO2 is emitted, it's about how many vehicles are on a given stretch of roadway. If they want pollution reductions but don't care about congestion the previously proposed plan is the way to go. If they want both, then no vehicles should get an exemption but a sliding scale would still provide an incentive to get a cleaner vehicle if you must drive into the city.