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  • Specs840i · 718

BMW 840i Convertible G15 vs Porsche 718 Boxster

Trip mapped at a glance. Charging stops visible, total duration predictable. Caralogy simulation at 130 km/h.

limousine · 2021 vs 2018 · Paris → Marseille · 775 km · 130 km/h
BMWPetrolPlus rapide

840i Convertible G15

333 ch · 2021

VS
PorschePetrol

718 Boxster

300 ch · 2018

Simulation trip
Assumptions: 130 km/h · start réservoir plein · mild weather

Result · total trip time

ABMW 840i Convertible G15

7h01no stop

0 stops · 104.27 €

Gap20 minin favour of 840i Convertible
BPorsche 718 Boxster

7h21charging included

4 stops · 470.89 €

Paris → Marseille · 130 km/h · Caralogy simulation
Measure840i Convertible G15718 BoxsterGap
Total time7h017h2120 min · 840i Convertible G15
Charging stops0 stops4 stops4 stops · 840i Convertible G15
Cost of energy used104.27 €470.89 €366.62 € · 840i Convertible G15

Visualise the trip

Both vehicles drive at 130 km/h. The difference comes from charging stops.

BMWPetrolFastest
840i Convertible G15
100%
1097 km
Range
Paris
0 km · departure
Marseille
775 km · Arrival 7h01
0
Stops
7h01
Duration
104.27 €
Cost of energy used
PorschePetrol
718 Boxster
100%
174 km
Range
Paris
0 km · departure
Refuel 1
5 min · +49 L · 105.72 €
Refuel 2
5 min · +49 L · 105.72 €
Refuel 3
5 min · +49 L · 105.72 €
Refuel 4
5 min · +49 L · 105.72 €
Marseille
775 km · Arrival 7h21
4
Stops
7h21
Duration
470.89 €
Cost of energy used

The 20-minute lead of the 840i Convertible G15 does not come from driving speed, but from 4 fewer charging stops on this route (0 vs 4).

Both vehicles drove at 130 km/h for the entire trip. The gap is built at the stops: no stop for the 840i Convertible G15 versus 4 stops totalling 20 min for the 718 Boxster.

Motorway consumption: the Caralogy methodology

The official WLTP figures (7,5 L/100km for 840i Convertible G15 and 9,8 L/100km for 718 Boxster) are measured on a mixed cycle averaging ~46 km/h. At a steady 130 km/h, aerodynamic drag weighs much more heavily - it grows with the square of speed. Caralogy calculates a motorway consumption specific to each vehicle based on its aerodynamic profile (SCx), weight and power curve - not a uniform correction factor. For this trip, the simulation yields 6,2 L/100km (840i Convertible G15) and 28,0 L/100km (718 Boxster). Full methodology: see the assumptions below the controls.

Energy cost breakdown for your trip Paris → Marseille

The cost per kilometre depends on the electricity rate applied to each segment - based on the energy source used at that point of the trip.

BMW 840i Convertible G15

SegmentEnergy usedDistanceConsumption€/kmCost (€)
Paris → Marseillefuel · 2.17 €/L775 km48 L consumed0.135 €/km104.27 €
Trip total104.27 €

Porsche 718 Boxster

SegmentEnergy usedDistanceConsumption€/kmCost (€)
Paris → Auxerre, A6fuel · 2.17 €/L174 km49 L consumed0.608 €/km105.72 €
Auxerre, A6 → Tournus, A6fuel · 2.17 €/L174 km49 L consumed0.608 €/km105.72 €
Tournus, A6 → Valence, A7fuel · 2.17 €/L174 km49 L consumed0.608 €/km105.72 €
Valence, A7 → Manosque, A51fuel · 2.17 €/L174 km49 L consumed0.608 €/km105.72 €
Manosque, A51 → Marseillefuel · 2.17 €/L79 km22 L consumed0.608 €/km48.02 €
Trip total470.89 €

What produces these figures

WLTP combined consumption
7.5 L/100 km · 9.8 L/100 km
Fuel tank
68 L · 54.1 L

Compare with another vehicle

Replace one of the two with an alternative from the same segment

BMWPetrol

840i Convertible G15

333 ch · 2021

PorschePetrol

718 Boxster

300 ch · 2018

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Frequently asked questions

On Paris → Marseille (775 km at 130 km/h), the 840i Convertible G15 arrives in 7h01 with 0 fuel stops.

WLTP consumption does not reflect motorway reality. Aerodynamic drag grows with the square of speed, so real consumption is 15 to 25 % higher than WLTP combined. Caralogy calculates a highway consumption specific to each vehicle based on its aerodynamic profile (SCx), weight and power curve.

Total time = driving time + charging time. Driving time is calculated at an average speed of 130 km/h on the motorway (adjustable). Charging time is calculated based on the real power curve of each vehicle, respecting the optimal 10 → 80 % range and the maximum power accepted by the chargers on the route.

No. The displayed cost covers only the energy consumed during the trip: kWh × energy rate, with a mix of home charging and DC fast chargers. Battery wear is a long-term ownership cost, not a trip cost.

On this trip, the energy used costs 104.27 € (840i Convertible G15) and 470.89 € (718 Boxster). For reference, an equivalent Mercedes S 450 (~9.0 L/100 km) would cost about 129 € in fuel.