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  • Specs840i · Boxster

BMW 840i xDrive Convertible G15 vs Porsche Boxster S 987: which is truly faster?

Simulated drag race 0 → 1,000 m in real time. Synchronised speed counters and stopwatch. Physics calibration on 7 manufacturer measurements.

limousine · 2021 vs 2010
BMWPetrol

840i xDrive Convertible G15

333 hp · 500 Nm · 1,915 kg · 2021

VS
PorschePetrolFaster

Boxster S 987

314 hp · 361 Nm · 1,380 kg · 2010

Parameters and assumptions

Simulation

Start
Standing, straight line
Surface
Dry asphalt, 23°C
Wind
None
Driver
1 person, 75 kg

Calibration

Splits
0–100, 0–200 manufacturer
Power curve
Real measurement (Caralogy)
VMax
Manufacturer limited
Transmission
Losses integrated in model

Physics model calibrated on manufacturer splits. The limited top speed is not the real aerodynamic top speed of the vehicles.

840i xDrive Convertible G15Boxster S 987
0–100 km/h5,30 s5,07 s+0,23 s
400 m standing start13,57 s13,19 s+0,38 s
1,000 m standing start24,59 s23,72 s+0,87 s
Top speed (electronically limited)250 km/h272 km/h−22 km/h
Power-to-weight ratio5,75 kg/hp4,39 kg/hpbetter ratio

Watch the race

Standing-start drag race, calibrated on manufacturer splits. The gap shows at each stage.

BMWPetrol840i xDrive Convertible G15
Speed
0km/h
Timer
0,00s
Distance
0m
PorschePetrolBoxster S 987
Speed
0km/h
Timer
0,00s
Distance
0m
100 m
200 m
300 m
400 m
500 m
600 m
700 m
800 m
900 m
1000 m
0m → 1000m
Gap0m

Stage-by-stage comparison

Simulated performance at each stage. Winner in green.

Palier840i xDrive Convertible G15Boxster S 987
0–30 km/h1,36 s1,35 stight gap
0–50 km/h2,25 s2,25 stight gap
0–80 km/h3,85 s3,85 s
0–100 km/h5,30 s5,07 s
0–120 km/h7,11 s6,64 s
0–160 km/h12,08 s10,76 s
0–200 km/h19,74 s17,15 s
400 m standing start13,57 s13,19 s
1,000 m standing start24,59 s23,72 s
Top speed limited250 km/h272 km/h

Under the bonnet

Manufacturer technical specifications. The power-to-weight ratio is the key physical factor in a drag race.

BMW

840i xDrive Convertible G15

5,75kg/hpcompensated by −535 kg
CharacteristicValueDetail
Power333 hp6 cyl
Torque500 Nm
Weight1 915 kgmanufacturer kerb weight
DrivetrainIntegrale (AWD)
Gearbox8-speed Steptronic
Porsche

Boxster S 987

4,39kg/hpratio better by 1,36 kg/hp
CharacteristicValueDetail
Power314 hpB6
Torque361 Nm
Weight1 380 kgmanufacturer kerb weight
DrivetrainPropulsion
GearboxDUAL_CLUTCH

The start: 0 to 100 km/h

Off the line, the Boxster S hits 100 km/h in 5.07 s versus 5.30 s for the 840i xDrive Convertible. The 0.23 s gap is negligible: both vehicles are neck and neck.

From 100 km/h to 400 metres

At 200 metres, the Boxster S is doing 143 km/h against 136 km/h for the 840i xDrive Convertible. The gap is 0.16 s. The gap remains stable from the start.

At 400 metres standing start, the Boxster S crosses the line in 13.18 s versus 13.56 s. The 0.38 s gap represents roughly 18 m of track - two to three car lengths.

Beyond 400 metres: top speed comes into play

Past 400 metres, the Boxster S continues to build its lead. At 600 metres, it runs at 199 km/h versus 190 km/h. At 1,000 metres, the Boxster S finishes in 23.72 s versus 24.59 s, with a 0.87 s lead.

What the numbers don’t tell you

Both rivals are electronically governed, but not at the same level: the 840i xDrive Convertible is capped at 250 (i.e. 155 mph - industry threshold) km/h, the Boxster S at 272 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 (5.75 kg/hp vs 4.39 kg/hp) and transmission (Automatic vs Automatic).

In European road use (130 km/h max), both vehicles reach the legal speed limit in under 8.18 seconds. The 0.23 s difference in 0 to 100 km/h is mostly felt in motorway merging and overtaking.

Compare with other alternatives

Swap one of the two models to explore an equivalent duel in the same segment.

Instead of 840i xDrive Convertible G15
BMW Z4 M40iBMW Z4 M40iBMW Z4 sDrive30i

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Z4 M40i vs Boxster S

Frequently asked questions

Over 0–100 km/h, Boxster S 987 wins (5,07 s vs 5,30 s).

840i xDrive Convertible G15 goes from 0 to 100 km/h in 5,30 seconds (calibrated simulation).

840i xDrive Convertible G15: 333 hp, ratio 5,75 kg/hp. Boxster S 987: 314 hp, ratio 4,39 kg/hp.

840i xDrive Convertible G15: 250 km/h. Boxster S 987: 272 km/h.