Expert answer

There has been a huge move towards diesel cars here in Ireland because of the change to the road tax and VRT laws in July 2008.

Since then, as you may or may not know, road tax and VRT are calculated according to a car's CO₂ emissions and because diesel cars use less fuel than petrol ones, their emissions tend to be lower.

When your father bought the Mazda6 in 2008 it may well have been better value than the diesel model. Now, there is much less difference between the price.

Before we move away from Mazda, there is now a very good range of diesel engines in the new Mazda6 and that might make the most cost-effective swap if he was happy with the car he has because you will most likely get the best trade-in price from a Mazda dealer. However, by the sounds of things he wants a change.

Covering only 10,000km a year we previously might have said that there was no real need to buy a diesel because you would not save the extra price of the car in fuel.

This point remains true, but the difference now is that the market has changed so much to diesel that petrol cars are likely to lose their value faster and become increasingly unwanted by used car buyers, so at this size of car, we would say yes, move to diesel. Also, if you do buy new, your father will most likely benefit from lower road tax.

Without knowing a budget it is difficult to point you in the right direction but from the cars you mention I'm guessing the budget is between €25,000 - €35,000. This does offer a lot of choice.

The 2004/2005 BMW 320d is certainly an option. Since the current shape model came out in 2005, we would encourage you to look at these, or even a 2006. The prices of these are quite competitive at the moment. A 2005 320d SE at a SIMI dealer would probably cost you between €15,000 - €17,000.

BMWs are always tempting to buy used, but you must choose one that has been properly serviced and cared for, because they can become more expensive to put right as they get older. The choice of used 320d models at the moment is vast so if you do go down that route, shop around. It is a great car and with the small mileage your Dad does it is unlikely to end up costing you too much.

If you want to go down the new route, there are a few that would spring to mind. The first is the Skoda Superb. This car is really brilliant and huge too. It is well made and loaded with equipment. If your Dad likes comfort then this will be right up his street.

Our choice would be the 2.0-litre TDI Comfort for €27,805. It is excellent value for money and comes with lots of creature comforts (cruise control, climate control, etc.), a 170hp diesel that is powerful, yet still frugal at 5.8 l/100km. Road tax on this car is €302 per year. For me, if I were heading out to buy a family saloon today, I wouldn't pass the Superb.

You mentioned some other cars there. The Jetta isn't a bad car, but it's been out a few years now and is probably due an update, so I wouldn't buy that new. The Audi A4 is nice. A new one is going to cost you from €34,060 before you start looking at optional extras, so a 2009 model would make sense with all the options already added. €35,000 should get you a nice 2009 TDI version with lots of the toys thrown in.

Please feel free to come back to us with more details if you like (just add a comment below), but for me I would probably have the Superb.

Expert answer

Well you haven’t said what your budget is but there are plenty of interesting cars that are available under the scrappage scheme.

Alfa Romeo’s Mito is a small premium hatchback, and its clean 1.3-litre diesel engine puts it in Band A; the 1.4-litre petrol and 1.6-litre diesel models fall into Band B. Prices start at €18,995 before you take away the government discount.

The Audi A3 with the 1.2-litre TFSI petrol, the 1.6-litre diesel and 2.0-litre diesel all qualify for scrappage, as does the Cabriolet version. The A3 3-door starts from €25,195 before scrappage discount, it’s €26,195 as a 5-door Sportback model, and €32,785 for the Cabriolet version before the €1,500 discount.

The A4 with a 2.0-litre diesel engine in either 120bhp, 136bhp and 170bhp all fall under Band B in either saloon or Avant form. Prices start from €34,060 (€32,560 with scrappage) for the diesel saloon and €36,460 (€34,960 with scrappage) for the Avant. The stunning A5, with a 170bhp 2.0-litre diesel engine, falls into Band B. Prices start at €44,265 (€42,765 with scrappage). You can also have the Audi A6 2.0-litre TDi with 136bhp, which is in Band B. This huge car starts from €39,735 (€38,235 with scrappage). The Audi TT diesel is a really superb car to drive. At €44,175 for the Coupé (€42,675 with scrappage), this is a brilliant buy and that fact that it costs €156 per year to tax makes it all the sweeter.

BMW also has a huge number of models that qualify for the scrappage scheme. Its 2.0-litre diesel is used in various power outputs across the 1-Series, 3-Series and 5-Series and these all have emissions of less than 140g/km, even when fitted with an automatic transmission.

The 1-Series is available with clean diesel engines ranging in power from 115bhp to 177bhp. Prices start at €24,900 for the 3-door 116d, €23,400 with the scrappage discount.

The BMW 3-Series starts from €33,310 for the 316d. All its models get €1,500 off from the government through scrappage. Largest of all is the 520d. Although there is a new model coming later in the year, the run-out models of the 520d are expected to sell well, especially with a price tag of €40,220.

Mercedes-Benz has a number of models that qualify under the scrappage scheme. The standout model is the C-Class Blue Efficiency 200 (136bhp), 220 (170bhp) and 250 (240bhp) manual versions, the E-Class 200, 220 and 250 manual version and the E-Class Coupé 220 and 250 models with manual transmission. Prices start at €36,500 (€35,000 with scrappage) for the C200 CDi, €41,200 (€39,700) for the E200 CDi and €47,700 (€46,200) for the E-Class Coupé E250 CDi.

Finally, what about the Volkswagen Scirocco? You can have the 1.4-litre TSi petrol or 2.0-litre TDi Sport model under the scrappage scheme. Prices start at €25,190 for the Scirocco (€23,690 with scrappage),

To answer your question though, which is fastest? We think it is the BMW 123d Coupe. It has emissions of 138g/km yet has a top speed of 238km/h and 0-100km/h time of 6.9 seconds. This is faster than the Audi TT TDi, which has a top speed of 226km/h and 0-100km/h time of 7.5 seconds.