Skip advert
Advertisement

Audi A6 3.0 BiTDI

Powerful diesel makes saloon even stronger

The Audi A6 and BMW 5 Series have been locked in battle for years. The latest generations of both have held Auto Express Best Executive Car titles and are the benchmark the new Lexus must face up to.

Worryingly for the GS 450h, though, the latest addition to Audi’s armoury is a potent diesel engine which is designed to offer class-leading performance. The new BiTDI is the most powerful V6 TDI yet, pumping out 309bhp and a whopping 650Nm of torque. We’ve tested the car in S line trim, and its sporty styling cues subtly enhance the A6’s slightly uniform and bland looks.

Advertisement - Article continues below

Still, if the exterior leaves you cold, the interior is sure to win you over. Beautifully clear yet upmarket instruments blend with Audi’s intuitive MMI control system and a perfect driving position to create a very functional and comfortable cabin.

The quality is faultless, while classy trim and swish design ensure it’s luxurious without being ostentatious. Standard kit is generous and the navigation screen gracefully slides out from the dash.

However, the real star of the show comes to life when you press the centre console-mounted start button. The 3.0-litre TDI engine hums gently at idle and is really smooth throughout the rev range, while the effortlessly rapid performance is nothing short of sensational. Quattro all-wheel-drive traction helps the A6 cover 0-60mph in only 5.6 seconds – but it’s real-world muscle that counts here, and the Audi doesn’t disappoint.

Skip advert
Advertisement
Skip advert
Advertisement - Article continues below

Used - available now

A6

2021 Audi

A6

39,142 milesAutomaticPetrol2.0L

Cash £25,649
View A6
A6

2023 Audi

A6

24,825 milesAutomaticPetrol2.0L

Cash £23,950
View A6
A6

2023 Audi

A6

31,633 milesAutomaticPetrol2.0L

Cash £19,950
View A6
A6

2023 Audi

A6

13,837 milesAutomaticPetrol2.0L

Cash £24,321
View A6

The eight-speed Tiptronic gearbox takes a while to react when you press the throttle at low speeds, yet with all that torque the engine doesn’t take long to get into its stride. And while the 535d is fractionally quicker in-gear, nobody will feel short-changed by the BiTDI’s performance, especially as the engine sounds so good. It’s as refined as you’d expect, but Audi has fitted a clever sound actuator in the tailpipe that artificially creates a sporty petrol-like exhaust note. Clever stuff.

The good news continues in corners, where the tightly controlled body roll and huge grip really impress and help this big saloon to feel smaller and more agile than its rivals. Also, Audi’s Drive Select system allows for fine-tuning of the chassis, although the differences between modes are subtle.

With a 20mm lower ride height and optional 20-inch wheels, our S line test car didn’t ride as well as the BMW, but the accurate steering, composed handling and scintillating performance ensure this is a diesel saloon to enjoy on a back road.

Unfortunately, despite stop-start the A6 has the highest emissions in the test – something that could deter company car drivers looking to minimise their tax bills. Could that be enough to cost this very desirable Audi victory in such a closely fought battle?

Details

Chart position: 2Why? We are big fans of the latest A6, and the new bi-turbo 3.0-litre TDI engine gives it even more punch and desirability. We test the car in sporty S line trim.

Skip advert
Advertisement

New & used car deals

Audi A6

Audi A6

RRP £52,110Avg. savings £5,629 off RRP*Used from £14,490
BMW 5 Series

BMW 5 Series

RRP £53,110Avg. savings £12,207 off RRP*Used from £33,195
Audi A5

Audi A5

RRP £42,760Avg. savings £3,966 off RRP*Used from £13,990
BMW 3 Series

BMW 3 Series

RRP £33,590Avg. savings £7,586 off RRP*Used from £9,700
* Average savings are calculated daily based on the best dealer prices on Auto Express vs manufacturer RRP
Skip advert
Advertisement

Most Popular

New Dacia Sandero is going EV, but there's still a place for petrol
Dacia Sandero render (watermarked) - front

New Dacia Sandero is going EV, but there's still a place for petrol

Next-generation supermini will provide a range of powertrains and a more rugged Stepway version
News
31 Aug 2026
Most and least reliable car manufacturers 2026
Most and least reliable car brands - header image

Most and least reliable car manufacturers 2026

These are the brands that are building the most reliable cars on UK roads, along with the ones that you might wish to avoid
Best cars & vans
30 Aug 2026
Luxury electric SUVs aren’t selling, and I know the reason why
Opinion - Lotus Eletre

Luxury electric SUVs aren’t selling, and I know the reason why

Deputy editor Richard Ingram thinks luxury SUVs are better suited to PHEV and range-extender tech than pure electric power
News
2 Sep 2026