Porsche Cayenne E-Hybrid vs BMW X4 M40d G02: which is truly faster?

Off the line, the Cayenne E-Hybrid hits 100 km/h in 4.74 s versus 4.94 s for the X4 M40d. The instant torque of 700 Nm from the electric motor makes the difference. At this point, the Cayenne E-Hybrid leads by 0.20 s and sits roughly 2 m ahead.

At 200 metres, the Cayenne E-Hybrid is doing 141 km/h against 137 km/h for the X4 M40d. The gap is 0.16 s. The gap remains stable from the start.

At 400 metres standing start, the Cayenne E-Hybrid crosses the line in 13.01 s versus 13.29 s. The 0.27 s gap represents roughly 13 m of track - two to three car lengths.

Past 400 metres, the Cayenne E-Hybrid continues to build its lead. At 600 metres, it runs at 195 km/h versus 190 km/h. At 1,000 metres, the Cayenne E-Hybrid finishes in 23.81 s versus 24.38 s, with a 0.57 s lead. Both vehicles have similar top speeds (253 vs 250 (i.e. 155 mph - industry threshold) km/h), preventing any comeback.

Both rivals are electronically governed, but not at the same level: the Cayenne E-Hybrid is capped at 253 km/h, the X4 M40d 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 7.77 seconds. The 0.20 s difference in 0 to 100 km/h is mostly felt in motorway merging and overtaking.