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  • SpecsBoxster · Z4

Porsche Boxster S vs BMW Z4 sDrive20i G29: 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.

sports car · 2010 vs 2021 · 15,000 km/an · Mixed · Petrol 95 2.17 €/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

APorsche Boxster S

3,327 €per year

10,2 L/100 km weighted · 22.18 € per 100 km · 1 533 L per year

Gap950 € per yearin favour of the Z4 sDrive20i (−29 %)≈ 438 L petrol 95
BBMW Z4 sDrive20i G29

2,376 €per year

7,3 L/100 km weighted · 15.84 € per 100 km · 1 095 L per year

The verdict changes with your usage
ProfileSplitAA · BoxsterBB · Z4Gap
City70 / 25 / 570 % city · 25 % road · 5 % motorway3,644 €2,726 €918 € · Z4
Mixed30 / 50 / 2030 % city · 50 % road · 20 % motorway3,327 €2,376 €950 € · Z4
Long-distance10 / 40 / 5010 % city · 40 % road · 50 % motorway3,020 €2,106 €914 € · Z4

Cumulative saving for the Z4 sDrive20i

1 year
950 €
3 years
2,851 €
5 years
4,752 €
10 years
9,505 €

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

What produces these figures

WLTP combined
10.1 L/100 km · 6.9 L/100 km
Powertrain
Combustion · Combustion
Power
314 ch · 197 ch
Kerb weight
1,380 kg · 1,420 kg

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Frequently asked questions

On a 100 km mixed trip, the BMW Z4 sDrive20i is about 30% cheaper than the Porsche Boxster S with default parameters. This ratio shifts with your actual energy prices - simulate for your profile.

The BMW Z4 sDrive20i is cheaper across all distances with default rates. If your energy prices differ significantly, simulate to see the real impact on your budget.