It’s a healthy line-up for the A7, because even the front-wheel drive 'Ultra' 3.0 TDI model can do 0-62mph in 7.3 seconds before running out of steam at a respectable 149mph. Adding the extra torque and four-wheel drive traction of the 215bhp quattro doesn’t improve top speed but does shave the 0-62mph time to 6.8 seconds.
The gap between the more powerful 268bhp 3.0 TDI quattro and the BiTDI is pretty small, as the former does 0-62mph in 5.7 seconds while the latter ticks it off in 5.2 seconds. The TFSI sits in between them, at 5.3 seconds for 0-62mph, while all three cars are electronically limited to the German gentleman’s agreement figure of 155mph.
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With such muscular performance on offer from the regular A7 range, it is almost unthinkable that there are two quicker Sportbacks – the S7 does 0-62mph in 4.6 seconds while the mental RS 7 can achieve the sprint in a scarcely believable (for this size of car) 3.9 seconds. Both are still pegged at 155mph, although on the RS 7 you can opt to raise that limiter to either 174- or 189mph. Performance models can drop the 0-62mph time to 3.7sec.
To return to the regular range, the 3.0-litre TDI V6 is a lovely unit, creamy and strong no matter what output it’s providing. The TFSI is also a nice engine but it is outmanoeuvred by the torquier, more frugal BiTDI.
Unless you’re absolutely set on saving the planet – by conversely buying a huge executive sports vehicle like the A7 – then avoid the ‘Ultra’ model. It’s all very worthy, utilising additional green technologies on the 3.0-litre 215bhp engine to cut emissions by 16g/km and improve combined economy by 7.4mpg next to the regular 3.0 TDI, plus it's the cheapest A7 of all in SE Executive specification at £46,865. But it masks a secret: it is the only two-wheel drive A7, and sadly that power doesn’t go to the rear axle. Yup, the upmarket A7 3.0 TDI ultra is front-wheel drive.