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Hi Rory,

Both cars use dual clutch semi-automatic gearboxes, which are pretty slick-shifting, but Volkswagen's DSG transmission just edges it for smoothness and quickness. 

On the emissions front it's rather bad news I'm afraid. If you're buying 2008 model year cars then you're looking at emissions of 189g/km for the Mondeo 2.0 TDCi Powershift and 175g/km for the Passat 2.0 TDI DSG. That means tax of €750 a year.

It gets a bit better if you can spool forward to 2010 when the Passat's emissions drop to 158g/km so that means a tax bill of €570 a year. 

Just for reference, the Mondeo 2.0 diesel auto gets an official 39mpg while the 2010 Passat with DSG gets 47mpg.

To be honest, if you can live without an automatic gearbox you would be better to go for the 1.6-litre diesel versions of either car. Both have decent performance and much better economy and emissions. For instance, a 1.6 BlueMotion Technologies Passat gets 62mpg and has emissions of just 118g/km so tax of €200 a year.

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Hi Eddie,

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Hi David,

OK, if you're determined to go diesel and you need a reliable 60mpg plus then the only safe option is to get yourself a Golf BlueMotion. Your Polo plus your budget should get you easily into one, but you have to remember that getting good fuel economy is actually all about your driving style. We recently managed to get better than 60mpg out of a 1.2 TSI petrol Skoda Rapid, and that was with four big blokes on board...

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Hi Blaithin,

In my personal experience the most efficient car I've ever driven was the Volkswagen Golf BlueMotion - it easily averages better than 60mpg in everyday driving and I'm not the most economical of drivers. €20k should get you a nicely specced 2010 or 2011 model.

How does that sound?

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Hi John,

Yup, a small diesel sounds like it should be ideal for you. Depending on what kind or size of car you need I'd recommend either a MINI Cooper D 1.6 (small and sporty), Opel Astra 1.3 CDTi (slower, but more spacious), Toyota Auris 1.4 D-4D (similar to Opel but probably more reliable) or that old favourite the Volkswagen Golf 1.6 TDI BlueMotion (ultra economical). Or, if you need more space how about a Skoda Octavia Combi estate 1.6 TDI or a Citroen C4 Picasso 1.6 HDi?

Help us with your needs and we'll narrow that down a little!

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Hi Phil,

"Most economical" is something of a loaded question as it's really much more dependant on your style of driving and the routes you use as much as anything else. 

What I can tell you though is the car in that class I've been able, consistently, to get the best economy from. It's a Golf. To be precise, it's the Mk VI Volkswagen Golf 1.6 TDI BlueMotion. Test driving it on a warm, sunny day with the air conditioning going and not paying a huge amount of attention to being economical, I managed an average of 65mpg. I haven't yet driven the latest Mk VII Golf BlueMotion but would suspect you could do even better again, possibly as good as 70mpg.

Come back to us if you need more assistance choosing.

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Hi Catherine,

OK, so what you need here is something spacious (kids, even just the one, take up a heroic amount of space, as you know), something economical for all that annual mileage and something comfy so that your buttocks survive all that mileage. I think you should stay with the current rough size of car, as some of the best bargains can be found in the mid-size saloon segment.

First up is a Volkswagen Passat. Ideally, you'd get the 1.6 TDI BlueMotion version, a car in which we once managed to drive from Galway to Glasgow and back on one tank of fuel. Or, what about a Ford Mondeo? You'll easily get a 2.0 TDCi model for that money, and there are very few cars quite so comfy on a long journey. Even BMWs and Mercs can't always match the Mondeo for seat comfort.

Of course, if you fancy the high life, and are prepared to compromise on space a little, then there's the BMW 3 Series. You'll get a 320d or 318d for that kind of budget, but shop around to make sure you get one in a dark metallic, with leather and preferably an automatic gearbox.

Finally, there's the Mazda6. Bit of an unsung hero of this segment, it's brilliant to drive, spacious, good looking and you should be able to track one down with Mazda's excellent 2.2-litre diesel engine under the bonnet. Reliable as it gets, it should chomp through your annual mileage with nary a worry. Find the even more handsome estate version if you can.

Come back to us if you need help narrowing this down.

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Hi Lorraine,

The 1.6-litre TDI engine is available in either 85- or 105hp outputs both of which have an official combined cycle consumption figure of 4.5 litres/100km (62.8mpg). The 105hp version is also available in BlueMotion trim with its longer gearing, unique bodystyling and other tweaks allowing for fuel consumption of 3.8 litres/100km (74. mpg). By way of comparision the 140hp 2.0-litre TDI Golf returns 4.8 litres/100km - or 58.9mpg in old money.

So while less powerful the 1.6 TDI is more efficient. All of the 1.6 variants also qualify for Band A tax of €160 whereas the 2.0 TDI is Band B, costing €225 annually. 

Just to throw a spanner into the works; over shorter journeys like the ones you outline a petrol powered model may actually prove to be more economical due to the time it takes a diesel engine to heat up and reach ideal operating temperature. And of course it will be cheaper to buy in the first place.

If you would like to discuss this further let us know. 

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Hi there,

It depends on your driving style, and on where you do most of your driving. If you’re in town all the time, and stuck in stop-start traffic, then it could be worth tracking down a Toyota Prius or a Honda Insight hybrid, bot of which should sip fuel in such circumstances. If you’re up on main roads and motorways all day long, then diesel is still a good idea. A VW Golf 1.6 TDI BlueMotion would be a solid bet for maximum economy then, although if you fancy something a little more stylish, a MINI Cooper D (with the 1.6 diesel engine) will crack 60mpg on a long run.

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Hi Teresa,

We spoke to Volkswagen and I'm afraid there's no permanent way to switch this off that it recommends. You'll just have to do it manually each time you start up if it bothers you.

From our perspective, this feature is becoming more and more common and we think it's a great idea. If all cars on the road used it think how much fuel could be saved in town. Likewise - and in contrast to what you've said - noise pollution would be reduced overall thanks to the lack of engine idling noise at traffic lights.

Don't worry about the starting motor wearing out either, as most cars with stop-start have heavier duty starters, along with systems to monitor their condition and prevent it being over used.