What Car?’s technicians drive new cars every week to capture our True MPG fuel economy data. Unlike official Government figures generated by a laboratory test, the numbers we publish are gained from real-world conditions.
This week we’re looking at executive saloons, including the Lexus IS300h petrol-electric hybrid and new Mercedes C-Class. These cars should be on the shortlist for anyone looking for a smart saloon with fuel efficiency as a top priority, because all offer in excess of 42mpg, while the top seven better 50mpg.
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. Mercedes C300 Hybrid - official 78.5mpg: True MPG 57.8mpg
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. The hybrid model falls more than 20mpg short of its official economy, but it is still the second most efficient saloon of this size that we've tested.
3. 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.
4. Audi A4 2.0 TDIe – official 65.7mpg: True MPG 55.5mpg
The Audi A4 handles well and has a wide range of powerful engines. However, like in its A6 sibling, the dashboard layout is far from the best in the business. The new A3 Saloon also shames its bigger brother as far as ride quality is concerned; the A4 is just too firm. However, thanks to reasonable list prices and strong resale values, the ownership costs are competitive.
5. Mercedes C200 Bluetec AMG Line – official 72.4mpg: True MPG 55.0mpg
This isn't the only Mercedes C-Class on the list, which says a lot about the new saloon. 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.
6. 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.
7. 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 the 5 Series from 0-60mph in 7.9seconds, when not in economy mode.
8. Mazda 6 2.2 Skactiv-D - official 64.2mpg: True MPG 54.0mpg
The Mazda 6 gets the same efficient diesel engines that impress in the larger CX-5, and it is an affordable car to run as a company user, thanks to its low CO2 rating. Its real-world economy is not bad either, although it is a way off the official figure. It is a smooth and strong engine, though, and manages the 0-60mph dash in just 9.0 seconds. The downside is a firm ride, which means the 6 isn't as good for motorway cruising as other cars on this list.
9. 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, 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.
10. Mercedes CLA220 - official 62.8mpg: True MPG 50.0mpg
The Mercedes CLA is the saloon version of the A-Class, but is blessed with a big boot and a load of standard equipment. The space doesn't spread throughout the cabin, though, as the rear seats are tight, especially in terms of headroom. We rate this diesel as the best in the range for the time being, and it performed well in our fuel economy tests, with a real-world rating of 50.0mpg.
11. 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.
12. Audi A6 2.0 TDI Ultra S line auto – official 64.2mpg: True MPG 49.8mpg
The Audi A6 is an impressively well-rounded executive saloon, offering decent refinement as well as a spacious, plush and well-built interior. The A6 isn’t as good to drive as the Jaguar XF, and the controls aren’t as intuitive as in a BMW 5 Series. Nevertheless, it’s an accomplished rival for both, and in Ultra S line spec it offers good performance, low emissions and plenty of equipment.
13. Volvo S60 2.0 D4 SE Lux Nav Manual – official 74.3mpg: True MPG 48.3mpg
If you are looking for something different in the executive class, the excellent-value S60 could be it. It scores highly for safety kit and comfort, but also proves to be an entertaining drive. The 2.0-litre engine manages to get emissions below the magic 100g/km - emitting just 99g/km of CO2 - but will also accelerate from a standstill to 60mph in 6.9 seconds.
14. Jaguar XF 2.2 Premium Luxury – official 57.7mpg: True MPG 42.5mpg
The XF might well be of near pensionable age compared to some of the competition, but it still stands up well as a good value, comfortable, stylish and fine-handling saloon. In fact, its combination of ride and on-road dynamics run the class-leading 5 Series close. The 2.2-litre 163bhp diesel trails the BMW when it comes to efficiency and performance, though.
We add new models to our True MPG database every week. Visit whatcar.com/truempg to see the full range of cars we’ve tested, and find out what you really can expect to achieve on UK roads.