Mercedes CLS saloon - MPG, running costs & CO2

Mercedes boasts efficiency gains from the CLS' clever engine technology, but the improvements are incremental rather than miraculous. It's difficult to make a car as big and heavy as this truly economical, although the smaller four-cylinder diesel engine shows how fuel-efficient this smooth four-door coupe can be.

Mercedes CLS MPG & CO2

Drivers in search of a truly economical CLS will be looking at the entry-point of the range, the 300d, but the six-cylinder 350d and 400d diesels don't disgrace themselves when you consider how much power they offer.

You can expect up to 46.3mpg from the 300d - an impressive figure for such a quick car - with a CO2 emissions figure of 142g/km. This means company-car-tax payers will face a Benefit-in-Kind (BiK) rating one off the top bracket. The more powerful 400d falls into the top 37% band for BiK, and economy drops to 41.5mpg.

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All the petrol engines make use of Mercedes' 'EQ Boost' mild-hybrid technology, which improves fuel economy and takes the edge off emissions. Don't expect a pat on the back from Greenpeace, though – the 350 can do 37.2mpg, the 450 returns 35.3mpg while the Mercedes-AMG CLS 53 manages just 31mpg.

BiK bands for the petrols match the diesels - the two most powerful options are in the top band, with the new 2.0-litre engine slipping into the next band down. They produce 163, 187 and 202g/km of CO2 respectively. With every CLS model priced comfortably above £40,000, you'll pay £465 each of the first five times your road-tax is due for renewal. After that point, it'll drop to £145 a year.

Insurance

Don't expect any Mercedes CLS to have inconsequential car insurance bills. The Association of British Insurers (ABI) has placed every four-wheel-drive model in group 50, the highest group. The smaller engines haven’t got a confirmed insurance group yet. We suggest that you shop around for insurance quotes before making a buying decision.

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Servicing

As with any Mercedes, a service is required annually or every 15,000 miles – whichever elapses first. Services alternate between minor and major, with certain additional operations such as brake fluid and fuel filter renewal considered separately. All routine maintenance can be covered by a service plan; these fixed-price packages can make budgeting easier, as well as reducing expense. Wear-and-tear items, including tyres that are at least 19 inches in diameter, will be expensive, and a car as heavy as the CLS will soon wear its expensive brake components out if regularly driven hard.

Warranty

Mercedes provides a three-year/unlimited-mileage warranty on every car it sells in the UK – about the norm for a premium brand. You can buy an extended warranty when this elapses, but this isn't quite as comprehensive as the warranty originally supplied with the car.