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840iPetrolvs420dDiesel
  • MotorwayMotorwayRange and charging
  • PerformancePerformance0-100, top speed
  • ConsumptionConsumptionYearly cost
  • Specs840i · 420d

BMW 840i xDrive Convertible G15 vs BMW 420d F32: which is cheaper to run?

What each kilometre costs, depending on your driving profile and how you charge. Annual projection and cumulative savings over 10 years.

limousine · 2021 vs 2020 · 15,000 km/an · Mixed · Petrol 95 2.17 €/L · Diesel 2.38 €/L · Methodology
Annual mileage
15,000 km
5,000 km50,000 km
Driving mix

30 % City · 50 % Road · 20 % Motorway

Fuel price
Petrol 95 2.17 €/L · Diesel 2.38 €/Lprix-carburants.gouv.fr — moyenne nationale du 05/10/2026 ; EDF Tarif Bleu Base au 01/08/2026 ; DC autoroute : moyenne des réseaux sans abonnement

Result · yearly energy cost

ABMW 840i xDrive Convertible G15

2,734 €per year

8,4 L/100 km weighted · 18.23 € per 100 km · 1 260 L per year

Gap1,184 € per yearin favour of the 420d (−43 %)≈ 546 L petrol 95
BBMW 420d F32

1,550 €per year

4,4 L/100 km weighted · 10.34 € per 100 km · 653 L per year

The verdict changes with your usage
ProfileSplitAA · 840iBB · 420dGap
City70 / 25 / 570 % city · 25 % road · 5 % motorway3,084 €1,666 €1,418 € · 420d
Mixed30 / 50 / 2030 % city · 50 % road · 20 % motorway2,734 €1,550 €1,184 € · 420d
Long-distance10 / 40 / 5010 % city · 40 % road · 50 % motorway2,464 €1,468 €996 € · 420d

Cumulative saving for the 420d

1 year
1,184 €
3 years
3,552 €
5 years
5,919 €
10 years
11,839 €

Energy only. Excludes purchase, insurance, servicing, depreciation.

What produces these figures

WLTP combined
8.0 L/100 km · 4.2 L/100 km
Powertrain
Combustion · Combustion
Power
333 ch · 190 ch
Kerb weight
1,915 kg · 1,605 kg

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Frequently asked questions

On a 100 km mixed trip, the BMW 420d is about 45% cheaper than the BMW 840i xDrive Convertible with default parameters. This ratio shifts with your actual energy prices - simulate for your profile.

The BMW 420d is cheaper across all distances with default rates. If your energy prices differ significantly, simulate to see the real impact on your budget.