Audi S6 Sportback e-tron vs BMW M340i xDrive G20: which is truly faster?

Off the line, the S6 Sportback e-tron hits 100 km/h in 4.08 s versus 4.46 s for the M340i xDrive. The instant torque of 855 Nm from the electric motor makes the difference. At this point, the S6 Sportback e-tron leads by 0.38 s and sits roughly 3 m ahead.

At 200 metres, the S6 Sportback e-tron is doing 146 km/h against 147 km/h for the M340i xDrive. The gap is 0.18 s. The challenger starts to claw back ground.

At 400 metres standing start, the S6 Sportback e-tron crosses the line in 12.52 s versus 12.56 s. The 0.04 s gap represents roughly 2 m of track - barely a car length.

Past 400 metres, the situation changes. The S6 Sportback e-tron maxes out at 233 km/h while the M340i xDrive keeps accelerating towards 250 (i.e. 155 mph - industry threshold) km/h. At 600 metres, the gap has dropped to 0.21 s.

Around 439 metres, both vehicles are level. This is the inversion point: the M340i xDrive overcomes its launch deficit thanks to a 17 km/h higher top speed.

At 1,000 metres, the M340i xDrive finishes in 22.70 s versus 23.58 s. The 0.88 s delta in favour of the M340i xDrive shows that top speed makes a clear difference.

Both rivals are electronically governed, but not at the same level: the S6 Sportback e-tron is capped at 240 km/h, the M340i xDrive at 250 (i.e. 155 mph - industry threshold) km/h. This isn’t a physical engine limit - it’s a manufacturer choice, usually for tyre safety or homologation reasons. Neither car reaches its true aerodynamic top speed.

Instant electric torque gives an advantage off the line. The higher top speed of the combustion engine gives an advantage over longer distances. The distance at which one catches the other depends on the top speed differential.

In European road use (130 km/h max), both vehicles reach the legal speed limit in under 6.65 seconds. The 0.38 s difference in 0 to 100 km/h is mostly felt in motorway merging and overtaking.