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Hi Adrienne,

OK, let me take that section by section...

(A) Most small crossovers use 1.5- or 1.6-litre diesel engines so you're going to average between 40- and 50mpg in any of them. Ignore the official consumption figures - they're not representative of real-world driving.

(B) Standard spec on most will include at least air conditioning and probably Bluetooth, but the items you've listed will push prices up into the €25-30k region.

(C) Kia, Hyundai and Mitsubishi have the best warranties on the market at the moment - seven, five and eight years respectively. Ford, Renault and Peugeot all offer five-year warranties too, while Fiat offers a four-year one. Most others have three-year cover. In terms of reliability, Japanese and Korean brands will almost always beat their European and American competitors.

Of the cars you're looking at, I'd say the strongest contenders are Honda's new HR-V, the Jeep Renegade, the Peugeot 2008 and the Kia Soul. All well worth a look.

Relevant reviews:

Honda HR-V review

Jeep Renegade review

Peugeot 2008 review

Kia Soul review

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Hi David,

There's no set warm-up time, as it depends on a number of factors, such as the ambient air temperature, how the car is being driven and which ancillaries are turned on. In general, diesel engines take longer to warm up than petrol (though the car makers are working on changing that) too.

I don't think there's anything wrong with your Mokka.

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Hi Aaron,

I'd tread very carefully. Although the engines in the Megane II are pretty robust, any and all of its electrical and electronic systems are suspect to say the least, and the suspension is prone to failure too. Only buy if it has a seriously flawless service history and appears to be in perfect condition - and even then I'd be wary.

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Hi Dan,

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Hi Stephen,

It depends. If it's the old non-turbo 1.4 75hp engine, then there shouldn't be any problems. It's a solid old lump, and as long as it's been kept serviced, it should be fine. If it's the more recent 1.4 TSI turbo or turbo + supercharger, then be a little more cautious - they're more complicated engines and I'd insist on the car having a full and complete Volkswagen dealer service history before buying.

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Hi Philip,

Not all marques and not all models use AdBlue as yet. AdBlue is a urea solution that can be injected into he exhausts of diesel cars to neutralise a significant proportion of their emissions of nitrogen oxides (NOx) - very much in the news at the moment of course. The rule of thumb is generally only that larger, more powerful engines need an AdBlue treatment system as many smaller engines don't need the assistance. Each manufacturer, and indeed each individual engine, will have its recommended AdBlue top-up times, and it will be directly related both to mileage and how much acceleration the car has been doing. You can top up the AdBlue tank yourself - a 1.5-litre refill should cost around €11-12.

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Hi Gary,

Volkswagen has confirmed that, following investigations, the EA288 engines, designed for EU5 and EU6 compliance, are not affected by the scandal surrounding the EA186 engines. In other words, the current Volkswagen diesel engines are fine and have been given a clean bill of health. If you've any lingering doubts over a car that you own, go to http://www.campaigncheck.ie and enter your reg number.

Read our full news story on this subject here

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Hi Ede,

It depends on which engine your Fiesta is powered by. The 1.4- and 1.6-litre TDCi diesels have change intervals of 10 years or 125,000 miles (just over 201,000km), while the petrol engines (1.25-, 1.4- and 1.6-litre) have timing belts that need to be changed every eight years or 100,000 miles (160,000km).

We'd always advise readers to have the timing belt changed sooner rather than later, especially if the service history of the car is unknown.

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Hi James,

The new Volvo S90 saloon, which will share its engines, chassis and, yes, that gorgeous interior, with the XC90, will go on sale in mid 2016 and will make a full public debut at the Geneva Motor Show next March. There'll be a massive V90 estate too we're told.

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Hi F D,

There does seem to be an issue with the turbo- and supercharged engines involving the timing chain and it seems to be because Volkswagen tried to stretch the service intervals too far. Now, your A3 may not have that particular engine, depending on the year and the engine power. The lower power 122hp version of the 1.4 TSI didn't have a supercharger, just a turbo so is simpler and doesn't seem to suffer the same issues. The more recent 150hp version also does without the supercharger, so the best thing to do is not panic - if you're concerned about the car, take it to your dealer, have it inspected and maybe insist on a more frequent oil change.