Good news, stingey green car fans. The government's shaken up the rules governing which cars can enter London's congestion charge zone for free. As of 4 January, any vehicle that emits 100g of carbon dioxide per kilometre or less, meeting the new Euro 5 emissions standard, qualifies for the government's Greener Vehicle Discount, making them exempt from the £10 per day charge. Full electric cars and plug-in hybrids also make the grade.
There's bad news too, though. Drivers of some cars that qualified for the 100 per cent congestion charge discount under the old rules will now have to pay up. Hybrid cars that emit more than 100g/km of carbon dioxide -- Lexus's sports utility hybrids and a raft of Honda hybrids, for example -- are no longer exempt.
In addition, new cars that would have qualified for exemption under the alternative fuel discount scheme will now have to fork out £10 if they enter the zone during prescribed hours. Anyone already signed up to the alternative fuel discount scheme will continue to receive the full discount.
Driving a qualifying vehicle could save you around £2,000 per year in congestion charge, which is fantastic news, we think you'll agree. So with this in mind, we thought we'd bring you a list of our favourite green cars in which you can roam the CCZ for free.
If there's one car built for nipping gleefully through central London traffic, it's the Leaf. Its all-electric power train emits absolutely no carbon dioxide from the tailpipe and the lack of an internal combustion engine means its cabin is eerily silent, making it a veritable oasis no matter how hellish your commute. Free parking and electricity top-ups are also available at one of the many recharging points throughout the city.
Price: £23,350 (after discount)
Without the Prius, the Greener Vehicle Discount list probably wouldn't even exist. This car, the world's first mass-market hybrid, helped show the world that cars could drive through big city centres without totally ruining air quality and poisoning innocent squirrels. It may be green, but it's a fun drive, too, thanks to next-gen gadgets such as a head-up display, automatic, hands-free parallel parking and a built-in hard drive that works as an audio jukebox.
Price: from £16,965
Fiat 500 TwinAir
Fiat's adorable 500 TwinAir gets in on the CCZ exemption act, where the standard Fiat 500 does not. It's powered by a tiny, two-cylinder 875cc engine that trades a traditional camshaft for electro-hydraulically controlled inlet valves. This, Fiat says, allows for more precise management of combustion, increasing efficiency and reducing the amount of fuel used. Its tiny engine produces an odd note -- it's reminiscent of a small motorbike -- but it pulls well around town, is surprisingly refined and comes with the option of the hugely impressive Blue & Me infotainment package.
Price: From £10,665
Volkswagen Polo 1.2 TDI 75 BlueMotion
The BlueMotion badge on this plucky Polo marks it out as the most efficient in the Polo range. Its tiny 1.2-litre diesel engine may spew more nox and sox particles into the atmosphere than some of its rivals, but who cares when its CO2 emissions are just 87g/km? Apart from asthmatics, we mean. The Polo also has excellent fuel economy. It returns a whopping 85.6mpg, so it's cheaper to run than almost any other car on this list.
VW Golf 1.6 TDI 105PS BlueMotion 5-dr
Polos don't hog the BlueMotion limelight for themselves -- the most fuel-efficient Golfs get the badge, too. Obviously, the Golf is a little larger than its supermini counterpart, so it can't really compete where economy is concerned, but the Golf BlueMotion still returns a staggering 74.3mpg and emissions of just 99g/km. The car's also refined and pleasant to drive. It may be the very antithesis of the iconic GTI model, but by golly it's good.
Seat Leon 1.6 CR TDI 105PS Ecomotive
Seat is a wholly owned subsidiary of the Volkswagen group, so you may not be surprised to learn the Leon Ecomotive is based heavily on the Golf platform. It offers the same emissions and fuel economy figures as its more esteemed cousin, along with the same performance and excellent build quality. What's more, it offers all of this for a price tag nearly than £2,000 lower than the Golf's.
Ford Focus 1.6 TDCi Econetic DPF StartStop
Ford has jumped on the low-emissions, high-economy bandwagon with its Econetic range. The Focus 1.6 TDCi Econetic with stop-start technology offers comparable figures to its Golf rival, just scraping under the 100g/km barrier and delivering 74.2mpg. It's also spacious, practical and refined. The only thing working against it is that it's marginally more expensive than the Golf BlueMotion and the fact the next version of the Focus, due in 2012, looks set to blow it out of the water.
Volvo S40 DRIVEe
Given Volvo's reputation for being safe and steady, you might be surprised to learn the S40 is one of the quickest cars on this list. It'll do the 0-60mph sprint in 10.8 seconds -- 1 second quicker than the Focus and Golf. It also has a higher top speed by a few miles per hour -- which is perfect if you're late for a business meeting on the Strand. Despite its extra pace, the S40 still achieves fuel consumption on a par with its rivals.
Tesla Roadster 250 Signature Edition
The Tesla Roadster might seem best suited for track use, as it's by far the fastest car in our list, but its electric powertrain means it's also ideal for commuting. It's exempt from the congestion charge and road tax, can be parked for free in some areas of central London and -- if you recharge it every day from one of the many free recharging points throughout the city -- you might never have to pay for any fuel.
Audi A3 1.6 TDi manual
Most models in the A3 range don't get anywhere near the required sub 100g/km CO2 rating required for congestion charge exemption, but the 1.6 TDi manual achieves this milestone by implementing some key modifications. It has a lower ride height, a tweaked underside and a modified final drive ratio -- the number of times the pinion attached to the output shaft on the transmission must turn in order to turn the axle once. Audi's also chucked in a stop-start system that switches the engine off when the car's at a standstill. Together, the changes make the a3 1.6 TDi manual one of the greenest cars on the road.
Update: A previous version of this story stated that the Honda CR-Z and Cadillac Escalade Hybrid were eligible for the exemption, but under the new rules that's no longer the case. Which is a shame, but makes more sense.
Tesla's Roadster is a sports car at heart, but its electric powertrain makes it ideal for the daily commute -- as long as you don't mind the lack of power steering and single people constantly throwing themselves at you.