Bmw 840i xDrive Convertible G15 vs Porsche Cayman 981 : which one is faster?
0-100 km/h, 400 m, 1000 m, top speed — physics simulation calibrated on 7 measures.
Simulation de performance
Race simulation at real speed
CONFIDENCE 90%Calibrated physics simulation: SCx via VMax, power curves, Crr via WLTP, drivetrain losses. Manufacturer 0-100 is the calibration target. Confidence 90 %.
Bmw 840i xDrive Convertible vs Cayman: chronicle of a drag race at 253 km/h
The launch: 0 to 100 km/h
Off the line, the Bmw 840i xDrive Convertible hits 100 km/h in 5.30 s versus 5.52 s for the Cayman. At this point, the Bmw 840i xDrive Convertible leads by 0.22 s and sits roughly 2 m ahead.
From 100 km/h to 400 metres
At 200 metres, the Bmw 840i xDrive Convertible is doing 136 km/h against 136 km/h for the Cayman. The gap is 0.09 s. The challenger starts to claw back ground.
At 400 metres standing start, the Bmw 840i xDrive Convertible crosses the line in 13.56 s versus 13.64 s. The 0.07 s gap represents roughly 3 m of track — barely a car length.
Beyond 400 metres: top speed comes into play
Past 400 metres, the Bmw 840i xDrive Convertible continues to build its lead. At 600 metres, it runs at 190 km/h versus 190 km/h. At 1,000 metres, the Bmw 840i xDrive Convertible finishes in 24.59 s versus 24.68 s, with a 0.09 s lead. Both vehicles have similar top speeds (250 vs 253 km/h), preventing any comeback.
What the numbers don’t tell you
Electronically capped at 250 km/h, the Bmw 840i xDrive Convertible never reaches its natural aerodynamic ceiling in this duel. That’s not a physical limit of the motor — it’s a deliberate manufacturer decision, typically tied to standard-fit tyre ratings or model-range positioning.
With two combustion powertrains, the difference comes down to power-to-weight ratio (5.75 kg/hp vs 4.70 kg/hp) and transmission (Automatic vs Unknown).
In European road use (130 km/h max), both vehicles reach the legal speed limit in under 8.30 seconds. The 0.22 s difference in 0 to 100 km/h is mostly felt in motorway merging and overtaking.
Bmw 840i xDrive Convertible is slightly faster than the Porsche Cayman to 100 km/h. The edge holds on standing starts but may narrow at higher speeds depending on aerodynamic load.