Skip to main content
CaralogyCaralogy
HomeBrandsRoad TripBudgetDuelGuides
Caralogy

The car comparison platform. Physics simulation, road trips, real costs.

Navigation
All brandsCar duelRunning costsMotorwayMethodology
Simulators
Motorway simulatorRunning costsPerformance duel
Brands
VolkswagenBMWMercedesToyotaTeslaAudi
FRENDEESIT
© 2026 Caralogy · All rights reserved
  1. Home
  2. /Motorway
  3. /sports car
A718vsB420iPetrol
  • MotorwayMotorwayRange and charging
  • PerformancePerformance0-100, top speed
  • ConsumptionConsumptionYearly cost
  • Specs718 · 420i

Porsche 718 Boxster vs BMW 420i Convertible G22

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

sports car · 2018 vs 2021 · Paris → Marseille · 775 km · 130 km/h
PorschePetrol

718 Boxster

300 ch · 2018

VS
BMWPetrolPlus rapide

420i Convertible G22

184 ch · 2021

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

Result · total trip time

APorsche 718 Boxster

7h21charging included

4 stops · 470.89 €

Gap20 minin favour of 420i Convertible
BBMW 420i Convertible G22

7h01no stop

0 stops · 90.81 €

Paris → Marseille · 130 km/h · Caralogy simulation
Measure718 Boxster420i Convertible G22Gap
Total time7h217h0120 min · 420i Convertible G22
Charging stops4 stops0 stops4 stops · 420i Convertible G22
Cost of energy used470.89 €90.81 €380.08 € · 420i Convertible G22

Visualise the trip

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

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
BMWPetrolFastest
420i Convertible G22
100%
1093 km
Range
Paris
0 km · departure
Marseille
775 km · Arrival 7h01
0
Stops
7h01
Duration
90.81 €
Cost of energy used

The 20-minute lead of the 420i Convertible G22 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 420i Convertible G22 versus 4 stops totalling 20 min for the 718 Boxster.

Motorway consumption: the Caralogy methodology

The official WLTP figures (9,8 L/100km for 718 Boxster and 6,1 L/100km for 420i Convertible G22) 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 28,0 L/100km (718 Boxster) and 5,4 L/100km (420i Convertible G22). 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.

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 €

BMW 420i Convertible G22

SegmentEnergy usedDistanceConsumption€/kmCost (€)
Paris → Marseillefuel · 2.17 €/L775 km42 L consumed0.117 €/km90.81 €
Trip total90.81 €

What produces these figures

WLTP combined consumption
9.8 L/100 km · 6.1 L/100 km
Fuel tank
54.1 L · 59 L

Compare with another vehicle

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

PorschePetrol

718 Boxster

300 ch · 2018

BMWPetrol

420i Convertible G22

184 ch · 2021

Other duels you might be interested in

JaguarVSPorsche

F-TYPE P300 vs 718 Boxster

AudiVSBMW

A4 40 TFSI vs 420i Convertible

BMWVSPorsche

Z4 M40i vs 718 Boxster

AudiVSBMW

A5 Avant vs 420i Convertible

Frequently asked questions

On Paris → Marseille (775 km at 130 km/h), the 420i Convertible G22 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 470.89 € (718 Boxster) and 90.81 € (420i Convertible G22). For reference, an equivalent BMW M340i (~9.5 L/100 km) would cost about 136 € in fuel.