I believe that by tackling congestion, we will tackle emissions. Cars that are moving emit less CO2 than those that are stuck at traffic lights, or in traffic jams. This is why I will not allow smaller cars into the Congestion Charge zone for free, or introduce Ken Livingstone’s £25 charge on large family cars.
–Candidate for Mayor of London, Boris Johnson, 2008 manifesto (PDF)
That’s another of the mayor’s election manifesto promises. “Smaller cars” being shorthand for “cars with smaller engines which therefore emit less carbon dioxide”. To put it in context, before the 2008 election, the hybrid Prius, at only just over 100 g/km CO2 was the car of choice for those who wanted a greenwash. There wasn’t much else on offer. But the long-term trend in improving fuel efficiency of conventional small cars meant that some were beginning to compete with the Prius on miles-per-gallon and carbon emissions — and today several diesel cars are well below 90 g/km CO2 (one of the reasons why driving is so cheap).
Ken’s “new technology exemption” for hybrid cars had been a way of nudging people’s choices in a direction that would support development of alternative car technology, while also being less bad for London’s air quality and emissions targets. (And Ken was proposing to compliment this incentive with a £25 disincentive for Chelsea tractors, which Boris also refers to above.)
Boris didn’t like all that nudging. Nudging people’s behaviour with taxes and charges was a nasty Nu Labour thing to do. He couldn’t get rid of the Congestion Charge completely because its success has nowadays given it popular support, and, more importantly, he needs the revenue from it. So his transport manifesto was simply saying that he would keep the central Congestion Charging zone, but that it would only be about congestion: it would be technology and emissions blind. By keeping the traffic moving “smoothly”, emissions would be reduced anyway, he said.
(Keeping traffic moving “smoothly” is itself a crazy fantasy, of course. Because latent demand for road transport in London is so much larger than supply, the roads will always be just on the edge of gridlock no matter what you do to “smooth” traffic flow, cut congestion, or add or remove capacity. But all that aside for now…)
I don’t really object to the mayor’s election stance on this issue. The problems caused by people driving into London are many and great; carbon emissions are just one of the problems, and we should be pursuing policies that solve as many of the problems as possible, not policies that solve (or rather, make a slight impact on) one while continuing to encourage the behaviour that causes all the other problems.
But this was a Boris manifesto pledge, remember. What happened next? In 2008, he kept his promise and dropped the proposed £25 Chelsea Tractor charge. In summer 2009 he began “reviewing” the exemptions rules. And finally on the 4th of January this year, the new rules came into force. The Prius lost its exempt status. So the mayor had finally achieved his technology and emissions blind congestion charge? Er. Not quite. The new rules allow smaller cars into the Congestion Charge zone for free — exactly what Boris promised not to do.
Most of the cars covered by the new “greener vehicle discount” are diesels — the biggest producers of the particulate pollutants that contribute to the deaths of thousands of Londoners from horrible lung diseases. And the mayor introduced this big new incentive, this great theatrical nudge, to encourage the uptake of diesel cars just weeks before the city faces a £300 million fine for its deadly air quality. (Not that Boris had a chance of keeping pollution within the thresholds even before this policy, given that he has done nothing substantial about the problem in three years.) Can’t imagine £300 million? Imagine the current round of London Borough council budget cuts not happening.
What changed the mayor’s mind? What happened to “smoothing the flow” with a flat charge? It’s almost as though smoothing the traffic flow is a meaningless phrase that can be used to justify any policy you like…
At War With The Motorist 
I think another point for a lot of us is that filling our city centres with aggressive people in speeding lumps of metal makes them very unpleasant places.
For all that folk say they want the sort of café culture, and pleasant centres that exist on the continent, it’s not an option with a river of stressed idiots inching their cars homewards/workwards 3 ft from your elbow.
It wasn’t just the Prius that was allowed in for free. Back then the (100%) congestion charge discount was based on the PowerShift Register which was a relic of the days of promoting LPG conversions for air quality purposes.
Vehicle types that were listed on the register and fitted with certified LPG conversions (along with EVs and hybrids) were allowed into London for free.
That included such green verhicles as…er… the V8 Jeep Grand Cherokee as well as the Porsche Cayenne hybrid and Lexus monsters.
Indeed “smoothing traffic flow” is a meaningless phrase used to justify just about anything. In TfL papers it used as a justification for measures as disparate as removing traffic lights (so traffic doesn’t stop so much, though ignoring the risk that this will generate more traffic) and reducing overall traffic volumes by bus and cycle priority measures. It is a stypical dog-whistle phrase that attracts the votes of those who believe that congestion is caused by traffic lights and road works and not by too many vehicles. So it is hardly surprising that BoJo has ended up doing what he said he wouldn’t do as the practical limits of smoothing flow in a saturated system have become apparent.
By the way, Consrvatives are supposed to be in favour of nudging (asa aginst the top-down nanny state) except when they are not. Just like they ae in favour of market-based price signals, except when they are not.