The sub-100 club: The greenest cars by emissions

Do you care about climate change or are you of the opinion that the whole thing's a big con? Regardless of your answer it's probably not the job of a motoring website to attempt to change your mind either way.

But even if you answered in the negative to the question above, there's a good chance you're considering buying a greener car, and if you're not then perhaps you should.

Why? Because whether you believe or not local, national and European governments will be looking to tax you to high heaven if you're keen on taking the little 'uns to school in your premium SUV.

If you're looking to buy a new car in the next few years, legislation from European and national governments will force up the cost of buying and running larger, more polluting cars. If you live within the boundaries of the Congestion Charge you'll be hit with another hefty penalty.

Quite regardless of your opinions on climate change it makes good financial sense to buy a cheaper car - particularly in light of the government's recent moves to remove road tax completely from the least-polluting cars.

And if you're a company car driver or are leasing a vehicle the Chancellor has made it cheaper for you to use a greener car.

Ken is already one step ahead - if your car emits under 120g/km of carbon dioxide you'll be exempt from the Congestion Charge.

So, if you're convinced by the financial case, or you simply want a greener car to do your bit, we'll give you a rundown of the greenest cars by CO2 emissions. The magical sub-100g/km club currently only has a few members, but with climate change on the agenda and government determined to act, its ranks can only grow.

Remember -the greener the car - the cheaper it is to run. The decision is yours.

Volkswagen Polo BlueMotion

• Emissions: 99g/km

• Fuel economy: 74.3mpg

• Price: £12,120

• Annual VED (road tax): 0

• Exempt from C-Charge? Yes

• Read Volkswagen Polo BlueMotion review

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The trail-blazer in the sub-100 club, the Polo BlueMotion was the first entry in the category and has the name recognition value.

Clever-clever warm hybrid elements such as brake energy regeneration, sleeker aerodynamics, rigid tyres, aircon that doesn't sap engine energy and longer gearing combine to drive down fuel economy from the Polo's turbodiesel engine, emitting less carbon dioxide as a result. There's also a diesel particulate filter to scrub soot from the exhaust.

BlueMotion 2 models add more gadgets, which push up consumption and nudge the Polo over the 100g/km figure - meaning an increase in road tax.

Frankly, with the base model, motoring doesn't get any greener - even the Prius can't match the Polo BlueMotion's figures.

SEAT Ibiza Ecomotive

• Emissions: 99g/km

• Fuel economy: 74.3mpg

• Price: £10,995

• Annual VED (road tax): 0

• Exempt from C-Charge? Yes

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As part of the massive Volkswagen family - soon to become the Porsche family - SEAT gets to use the best bits of Volkswagen's technology.

As a result the greenest version of the Spanish marque's supermini - the Ibiza - essentially shares all the same gadgetry as the Polo BlueMotion - returning identical figures for fuel economy and emissions and - ignoring the grand that the SEAT model knocks off VW's car - your wallet.

Green motoring doesn't get any cheaper - the Ibiza Ecomotive is the cheapest greenest car on the block.

MINI One D

• Emissions: 104g/km

• Fuel economy: 72.4mpg

• Price: £14,190

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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• Read MINI One D review

Benefitting from BMW's quite brilliant EfficientDynamics programme, the MINI One diesel engine returns the same carbon emissions figure as the Toyota Prius - proving you don't need a hair shirt if you're going to own a green car.

EfficientDynamics uses the same tricks as Volkswagen's BlueMotion technology to ration fuel and cut resulting emissions, with the addition of Stop-Start technology that cuts the engine while stuck in traffic.

The above review is for a version of the MINI One D prior to the introduction of EfficientDynamics, but is testament to how damn driveable the One is. Factor in its green credentials and low running costs and you have clean-conscience fun motoring.

Toyota Prius

• Emissions: 104g/km

• Fuel economy: 65.7mpg

• Price: £17,777

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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• Read Toyota Prius review

The Daddy of the clean-car brigade - the Prius is a genuine pioneer in motoring, constituting the first petrol-electric car on the roads and still the best car of its type by a country mile.

The Prius uses an electric motor in tandem with an efficient petrol engine to drive down fuel economy and emissions. All the usual energy-saving tricks combine with a CVT gearbox and a dozen other nifty tricks to allow the Prius to drive economically and make an ella-electric driving mode possible.

Celebrities love the Prius, Jeremy Clarkson hates it. It looks awful and there's a certain air of smugness surrounding the car, but it's a genuine innovation and will save you cash year-upon-year, even if it won't exactly save the planet.

Skoda Fabia GreenLine

• Emissions: 104g/km

• Fuel economy: 69mpg

• Price: £11,490

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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Eschewing the fancy-pants gadgetry of the BlueMotions, EfficientDynamics and hybrid models of this world, Skoda has simply stripped all the unnecessary weight out of the Fabia GreenLine.

There's no spare tyre, and lighter materials in tandem with a few aerodynamic tweaks mean that the GreenLine comes in significantly lighter than common-or-garden Fabia models- meaning less fuel consumption and less carbon dioxide emitted.

Honda Civic Hybrid

• Emissions: 104g/km

• Fuel economy: 61.4mpg

• Price: £17,100

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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• Read Honda Civic Hybrid review

The second hybrid off the block, the Civic IMA hybrid has never been a great car and it's now showing its age with a steep list price and economy and emissions figures that are easily trumped by cars that are much cheaper and much more fun to drive.

You'd be frankly insane to buy one these days as the Civic Hybrid loses out to other cars in every category, and the Prius is an all-round better car if you must have a hybrid.

Still, that doesn't mean it's any less of an achievement and the figures are not to be sniffed at. Not to be outdone Honda has gone ahead and started leasing hydrogen fuel-cell vehicles in LA - a car with potentially zero emissions. It won't be on sale 'til next decade though, so for now it's a Civic Hybrid.

Toyota Aygo/Citroen C1/Peugeot 107

• Emissions: 109g/km

• Fuel economy: Various - up to mid 60s

• Price: Various, from around £7,000

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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• Read Peugeot 107 review

The Toyota Aygo, Citroen C1 and Peugeot 107 are essentially the same model so appear here together. There's nothing to write home about in terms of weird technology on these cars- they're simply very small, light and frugal.

All are zippy city cars that are perfect for urban driving, especially if you live in London...

MINI Clubman D

• Emissions: 109g/km

• Fuel economy: 68.9mpg

• Price: £15,400

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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• Read MINI Clubman review

An estate car that not only raises two fingers at Transport for London but flips the bird at Alastair Darling's eyebrows.

The Clubman is basically the MINI One D with all the same clever technology to reduce the amount of go-juice the estate sips on. Again, our review isn't of the Clubman D, but gives an impression of how much fun the MINIs are.

As it's slightly bigger the figures aren't quite as impressive, but parent company BMW continues to do impressive things with its EfficientDynamics tech.

Fiat 500 Multijet

• Emissions: 110g/km

• Fuel economy: 67.3mpg

• Price: From £9,300

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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• Read Fiat 500 review

The coolest car on the block at the moment just got cooler, greener and cheaper.

Equipped with Fiat's 1.3-litre MultiJet engine, the 500 returns excellent figures for economy and emissions.

Fiat packs a lot of kit into the 500 too, so you won't want for gadgets. A sub-100 Fiat 500 is on the cards for later in the year.

Citroen C2

• Emissions: 113g/km

• Fuel economy: 68.9mpg

• Price: From £9,975

• Annual VED (road tax): £35. £20 from 2009

• Exempt from C-Charge? Yes

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• Read Citroen C2 review

Citroen's supermini has excellent figures across the board - it's green and cheap, and there are often discounts to be had on Citroen models.

Fun to drive, and fairly good-looking the C2 is good, clean fun at a reasonable price.