BMW M440i xDrive Convertible G22 vs Porsche Boxster: which is truly faster?

Off the line, the M440i xDrive Convertible hits 100 km/h in 4.96 s versus 5.72 s for the Boxster. At this point, the M440i xDrive Convertible leads by 0.75 s and sits roughly 8 m ahead.

At 200 metres, the M440i xDrive Convertible is doing 140 km/h against 132 km/h for the Boxster. The gap is 0.56 s. The challenger starts to claw back ground.

At 400 metres standing start, the M440i xDrive Convertible crosses the line in 13.18 s versus 13.99 s. The 0.81 s gap represents roughly 37 m of track - a gap visible to the naked eye.

Past 400 metres, the M440i xDrive Convertible continues to build its lead. At 600 metres, it runs at 196 km/h versus 187 km/h. At 1,000 metres, the M440i xDrive Convertible finishes in 23.87 s versus 25.24 s, with a 1.38 s lead. Both vehicles have similar top speeds (250 (i.e. 155 mph - industry threshold) vs 244 km/h), preventing any comeback.

The M440i xDrive Convertible features all-wheel drive (AWD) against the Boxster’s RWD. At low speeds (0-30, 0-50, 0-80 km/h), AWD doubles the driven contact area: all four wheels transmit torque to the road, virtually eliminating wheelspin at launch. This traction advantage is decisive in the range where the motor delivers peak torque, before power and aerodynamics take over.

Both rivals are electronically governed, but not at the same level: the M440i xDrive Convertible is capped at 250 (i.e. 155 mph - industry threshold) km/h, the Boxster at 262 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.

With two combustion powertrains, the difference comes down to power-to-weight ratio (5.05 kg/hp vs 5.15 kg/hp) and transmission (Automatic vs Unknown).

In European road use (130 km/h max), both vehicles reach the legal speed limit in under 9.00 seconds. The 0.75 s difference in 0 to 100 km/h is mostly felt in motorway merging and overtaking.