Audi A4 2.0 TDIe

If you’re looking for incredible efficiency but don’t want to shout about it, this is the car for you. The A4 TDIe returns fantastic economy and emits amazingly low CO2, yet it looks exactly the same as any other A4. It drives like one, too. The steering is communicative and there’s more grip from the low-rolling-resistance tyres than you’d expect. While the BMW 316d is marginally better to drive, as an overall package the Audi has it beaten.

Here’s an executive saloon with a supermini-sized drinking habit! We put the 316d – BMW’s most frugal 3-Series – through its paces. And now it’s time to see if Audi’s greenest A4 ever can match it.

The A4 2.0 TDIe is the third car to earn the ‘e’ prefix – which marks out the most efficient models in the range – following the A6 2.0 TDIe and A3 1.9 TDIe. As with the fuel-sipping A6, the A4 is powered by a version of the company’s familiar 2.0-litre turbodiesel, tuned to 134bhp.

It’s by no means the least powerful model in the range, but the TDIe is easily the most economical, returning a superb 61.4mpg combined and putting out 120g/km of CO2. That’s enough to comfortably eclipse the standard 118bhp 2.0 TDI, by 3.8mpg and 9g/km. So, how can a relatively powerful and regular-looking saloon achieve such impressive figures?

Scan the exterior, and there is hardly anything to give the game away. This has to be the most modest eco car on the road, with not so much as an ‘e’ badge in sight! But for eagle-eyed Audi fans, the clues come from blanked-out slats in the front grille and a 20mm reduction in the ride height. Both help the new car to slip through the air with minimum disturbance. Look beneath the car, and you will also find an extra piece of underbody trim, to streamline the flow of air underneath.

By far the biggest factor in the cut in CO2 output is the Start-Stop system, which Audi credits with slashing 5g/km from the total. It’s also touted as the fastest package of its kind on the market – firing the engine in two-tenths-of-a-second when you depress the clutch to select a gear.

Other eco modifications include a higher final drive ratio for the six-speed manual gearbox, a power-steering pump that switches on only when it’s required and harder-compound low-resistance tyres.

In addition, there’s a brake energy regeneration set-up. This stores the heat created during a braking manoeuvre as electricity in the car’s batteries, to take load off the engine next time you accelerate. Plus, a gearshift indicator features in the instrument cluster to help drivers change up at the most efficient time.

Yet despite the taller ratios, the engine pulls hard, and ensures the car feels more muscular than the 114bhp BMW. In fact, even on the narrower and firmer low-drag tyres, you’d struggle to tell that this A4 has been tweaked for economy. While it’s not as nimble as the rear-wheel-drive 3-Series, the Audi steers beautifully and grips very well in corners.

The lowered suspension helps to eliminate body roll, but the car doesn’t ride as hard as high-spec S line models – it gives a pleasing compromise between the two. As with any A4, the brakes and gearshift operate with a satisfying, well engineered feel.

Shorter springs help to give the car a sportier look from the outside – but Audi really has the competition licked inside. From the intuitive dial for the MMI cabin control system to the superb finish throughout, it’s a superb place in which to spend time. Plus, folding rear seats give the Audi a practicality advantage over the BMW.

There’s a choice of standard or SE versions – we drove the latter – and A4 TDIe prices start from £23,340. That’s £10 more than the 316d, which is great value considering you get extra power, similarly high economy and a top-notch interior. It makes you wonder, if the e modifications are so seamless and effective, why can’t Audi apply them as standard across the range?

Rival: Mondeo ECOnetic
Not only is the Ford £3,000 cheaper than the new Audi, it drives beautifully, too. But with 53.3mpg economy and 139g/km emissions, it lags some way behind the A4.