Real-world MPG: Most economical saloon cars

* Nine saloon cars that achieve more than 50mpg * Mix of executives, hybrids and family saloons  * Results indicate real-world fuel economy...

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John Howell
22 Sep 2014 8:30 | Last updated: 14 Jun 2018 0:3

Have you ever noticed that the fuel economy the manufacturer told you your car would achieve, doesn’t match what happens in the real world?

What Car?’s dedicated team of True MPG testers are working tirelessly to bring you a more realistic picture of things. Our efforts are focused on bringing you the most up-to-date news of which models are truly the most economical cars you can buy.

This week we’re taking a look at the most economical saloons that achieve an average of more than 50mpg in the real world. We have a shortlist of nine cars, which includes executives and family saloons, powered by a mix of diesel or hybrid engines.

1. Lexus IS 300h – official 64.2mpg: True MPG 59.6mpg

The low CO2 emissions of the Lexus IS300h mean that it’s cheaper to run than diesel rivals for business users. The lower-spec IS models have the best ride, but it’s a shame that the CVT gearbox causes the petrol engine to drone loudly because in other ways the hybrid is a rather refined car. Lexus’s reputation for excellent reliability and dealer service help make this a compelling company car option.

2. BMW 320d Efficient Dynamics – official 68.9mpg: True MPG 56.0mpg

The BMW 3 Series’ best executive car crown was snatched by the Audi A3 Saloon in our 2014 Car of the Year Awards. The BMW still has plenty of appeal, though. This version has CO2 emissions of just 109g/km and should prove incredibly frugal. It’s disappointing that you need to add the optional adjustable suspension to make it ride and handle as it should, but once you do the driving experience is about as good as it gets.

3. Mercedes C200 Bluetec AMG Line – official 72.4mpg: True MPG 55.0mpg

The Mercedes C-Class has been fully reworked to take the fight to BMW in the mid-size executive class. If your priority is ultimate handling and chassis balance, then the 3 Series is still the best. Alternatively, if you are swayed by cabin finish, then you’ll be hard-pressed to fault the C-Class’s beautifully built and stylish cabin. If you opt for the Airmatic suspension you'll get a limo-like ride at speed and good handling. Unfortunately, while efficient, the 1.6-litre Renault-sourced diesel sounds gruff and needs to be worked hard to make decent progress.

4. Mercedes E300 Hybrid – official 65.7: True MPG 54.6mpg

Despite a recent face-lift the E-Class still doesn’t match the BMW 5 Series for dynamics or interior quality. However, it’s still comfortable to ride in and has lots of interior space. The hybrid engine makes it the most economical car in its class, and with CO2 emissions of 109g/km it makes sense as a company purchase. However, its list price makes it a seriously expensive purchase for private buyers.

5. BMW 520d SE – official 62.8mpg: True MPG 54.5mpg

The fact that the 5 Series almost equals the E300 Hybrid with a diesel engine alone and costs nearly £10,000 less is a good achievement. It’s also the best executive car in terms of refinement and quality, as well as one of the best handling if you add the optional adaptive damping. The 2.0-litre diesel engine is smooth and will haul it from 0 to 60mph in 7.9seconds, when not in economy mode.

6. Mazda 6 2.2 Skyactiv-D 150 – official 67.3mpg: True MPG 54.0mpg

The 148bhp diesel is the least powerful on offer in the 6, but delivers more than enough performance to suit most people’s needs. Also, bearing in mind that the 6 is a relatively big car, it backs up its impressive economy with low CO2 emissions of just 108g/km. Its size means it is also practical, too, with 483 litres of boot space and generous accommodation for four adults – although rear headroom is a little tight for taller folk. Only a hard ride and some suspect cabin materials spoil the party.

7. Kia Optima 1.7 CRDi 2 – official 57.6mpg: True MPG 53.2mpg

The Optima is a saloon with striking looks and an even more striking seven year/ 100,000 mile warranty to add peace of mind to it’s frugal economy. It has an even bigger boot than the Mazda 6, managing 505 litres, but although there’s plenty of space in the front and excellent legroom in the rear, like the 6, it also suffers from reduced rear headroom. The rest of the car is okay, but not up with the class best; a jittery ride and poor cabin materials are amongst the things that let it down.

8. Lexus GS300h – official 60.1mpg: True MPG 51.4mpg

The GS is a very comfortable car to cruise in and comes as standard with Lexus’s excellent build quality and reliability. In hybrid form it makes a lot of sense as a company car purchase with CO2 emissions of 113g/km, and proves itself a very quiet and refined package, especially around town. Dynamically it doesn’t match the BMW 5 Series or Jaguar XF. It’s also not as roomy inside as you might expect, plus the boot is compromised by the battery pack.

9. Audi A3 Saloon 2.0 TDI 150 S line auto – official 68.9mpg: True MPG 51.2mpg

We crowned the Audi A3 Saloon our 2014 best executive car, because is does so many things so well. It’s cheaper than a BMW 3 Series, handles well, has a beautifully crafted cabin that feels like it’s been taken from a luxury saloon costing three times as much, and with the 2.0-litre 150 diesel engine it’s efficient and clean – producing just 105g/km of CO2. The only downside is that it’s less practical than the Sportback version, and make sure you deselect the standard sports suspension, which ruins the ride.

Want to find out what you can really expect to achieve on UK roads? Visit to see the full range of cars we’ve tested. We add new models to our True MPG database every week.