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Hi Colette,

We'll work from official figures here. Mazda quotes 4.3 litres/100km (65.7mpg) for the Mazda3 fitted with its 115hp 1.6 diesel engine. That applies to all versions of the five-door hatchback and four-door saloon the diesel engine can be had in.

Hyundai, meanwhile, quotes 4.1 litres/100km (68.9mpg) for its 110hp 1.6-litre diesel engine - in manual guise - so that car wins by a nose.

We wouldn't expect there to be much in it for the average driver though, as the Mazda has a little more performance (specifically torque), which means that the driver has to try a little harder in the Hyundai to achieve the same speeds.

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Hi John,

Yup, that seems like a good price, assuming the condition is good and all the service history is up to date. Make sure it's been in for a recall to have the steering system looked at and another one to reprogramme the engine control unit to stop it mistakenly kicking in to 'limp home' mode. 

A word of caution though; this car comes from an era when Mercedes-Benz was having a terrible time with build quality, and while the C-Class is generally well-made, we have heard reports of myriad problems, from small things like faulty door locks and handbrake linkages, to major items like engine injectors and ECUs. Buy carefully.

Let us know how you get on

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Hi John,

I'd go for the 1.3. True, it's not as grunty as the 1.7, but the 1.7 is a truly ancient engine, able to trace its roots all the way back to the early nineties when Isuzu first designed it and no-one in General Motors knew what the heck this de-hee-zel stuff was and they sure weren't going to put it in a car. The 1.3 by contrast was co-developed with Fiat in the early 2000s so is a much fresher, more high-tech design and it's a better engine all-round.

Both are a touch noisy compared with the best latest-gen diesels, but again the 1.7 is far worse in this regard and also has an annoying tendency to stall when pulling out of junctions. So go for the 1.3. A cracking little engine.

Hope that helps

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Hi Peter,

OK, there was no 1.3 diesel Hyundai i30, it was always a 1.6 diesel although there were lower and higher power versions. We found a couple of classified ads purporting to be 1.3 diesel i30s, but they must be typos. The Astra is definitely available with a 1.3 CDTi diesel though (a unit co-developed with Fiat a number of years ago) and while it's a fine engine and the Astra is a fine car, it's the Hyundai we'd go for - it's economical, cheap to tax and endlessly reliable. It's also far better to drive than you might expect (it even drew admiring comparisons to the class handling champ, the Ford Focus, at its time of launch) and is spacious and comfy to boot.

That said, if you're thinking of the Hyundai, you have to also consider the Kia cee'd. Launched in 2006, it's mechanically identical to the Hyundai, arguably a little sharper to drive and, depending on the mileage, a 2008 model should still have two years of Kia's seven-year warranty to run.

To be fair, you won't go wrong with either.

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Hi Diarmuid,

On the site we have a full test of the XF Sportbrake estate here, powered by the diesel engine. I never added in the average economy figure as my driving that week was mostly in an urban setting. For the record, it used about 9.0 litres/100km (31.4mpg). It should do a lot better on the motorway.

Is that of help?

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Hi Barbara,

Yes, it’s due to arrive in 2019 (and will probably be shown off at next year’s Geneva Motor Show in February) and will be based on the same TNGA chassis as you’ll currently find under the Toyota Prius and CH-R. It will definitely use the same new 1.5-litre petrol engine as installed in the updated Yaris, and will also get the 1.6-litre diesel bought-in from BMW and already being used in the Avensis and Verso. There is likely to be a hybrid version too, but that’s not guaranteed as yet.

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Hi Philip,

The thing with Italian cars is that they're like the apocryphal little sister. When they're good, they're very, very good. When they're bad, they're 'orrible.

The Multipla is actually one of the more robust Fiats, and speaking from personal experience the 1.9 JTDM diesel engine seems to take all manner of abuse and high mileage in its stride.

The best bet seems to be to avoid the 1.6 petrol model, and check to see if a diesel is down on power or displaying obvious flat-spots in the power delivery. If so, it could be an exhaust gas recirculation valve, or a more serious crankshaft wear issue. 

Other than that, check and make sure that everything electronic is working right. Fiat has come a long way on reliability since the bad old days but irritating electrical gremlins remain the brand's Achilles heel.

Let us know how you get on

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Hi John,

With that kind of mileage, I think you should go for the petrol Avensis. Yes, it’ll be a little higher in tax costs, but you’ll get it for less than the diesel, and have lower maintenance costs. 

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Hi Patsy,

BMW offers three different diesel engines with xDrive four-wheel drive in the X3, the xDrive20d, xDrive30d and xDrive35d. The xDrive20d can be had with a manual or automatic gearbox and the official figure is 50.4mpg (5.6 litres/100km) no matter which transmission is fitted. The xDrive30d and xDrive35d are only available with automatic gearboxes and the official fuel economy figures are 47.1mpg and 46.3mpg respectively (6.0- and 6.1 litres/100km).

Those figures won't be obtainable in the real-world, obviously! We spent time with the xDrive20d during snowy conditions a few years back (read the full review here) and averaged 34mpg (8.3 litres/100km), though in normal conditions it should do a lot better than that. We also tested the xDrive30d (read that full review here), though apologies, but I didn't record the average fuel consumption figure at the time...

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Hi Patrick,

I've always had a bit of a soft-spot for the current C5. No, it's not as sharp to drive as a Mondeo or Passat, but it's a lovely, comfy car with tremendous long-haul refinement. Pick of the bunch is the 1.6 HDi diesel model and you should get an easy 50mpg out of it.

As for faults, check for a chuffing sound from the engine when it's running, as that could indicate that the fuel injectors are in need of replacing. Make sure it's had a cambelt change and watch for diesel particulate filter warning lights, which indicate that it needs a good long run at high engine speed to burn the collected diesel soot out of the filter. Suspension problems are quite common - usually worn ball-joints or bushes. Other than that, they're pretty solid.