Car comparison

BMW 4 Series Convertible (G23) 420ivsBMW X3 (G01 LCI) · Facelift 2021 20i

Compare specs, acceleration, fuel consumption, dimensions, practicality, and estimated running costs side by side.

New comparison

BMW 4 Series Convertible (G23)

420i

184 hp1998 ccGasolineRWDAutomaticTurbochargedCabriolet / convertible2020-2024

BMW X3 (G01 LCI) · Facelift 2021

20i

184 hp1998 ccGasolineRWDAutomaticTurbocharged2021-2024

Comparison overview

Use the estimates as comparison hints and verify exact figures before making decisions.

BMW 4 Series Convertible (G23) 420i

Quickest 0-100 km/h
8.2 s
Fastest top speed
236 km/h
147 mph
Most powerful
184 hp
137 kW
Highest torque
300 Nm
221 lb-ft
Lightest
1,690 kg
3,726 lb
Best power-to-weight
109 hp/t
81 kW/t
9.2 kg/hp
Lowest combined fuel consumption
6.1 L/100 km
38.6 mpg US
46.3 mpg UK
Best estimated range
967 km
601 mi
Best performance score
48/100
Best economy score
90/100

BMW X3 (G01 LCI) Facelift 2021 20i

Largest trunk
550 L
Best overall score
56/100
Best practicality score
77/100

Specification comparison

Specification comparison
Model	BMW4 Series Convertible (G23)420i	BMWX3 (G01 LCI)Facelift 202120i
Power	184hp137kW	184hp137kW
Torque	300Nm221lb-ft	300Nm221lb-ft
Curb weight	1,690kg3,726lb	1,710kg3,770lb
Gross weight	2,185kg4,817lb	2,400kg5,291lb
Top speed	236 km/h 147 mph	215 km/h 134 mph
To 99% top speed	107.5s99% target: 234 km/h / 145 mph Calculated	103.1s99% target: 213 km/h / 132 mph Calculated
0-100 km/h	8.2s	8.2s
0-200 km/h	36.3s Calculated	51.5s Calculated
0-60 mph	7.8s Calculated	7.7s Calculated
Fuel consumption	6.1L/100 km38.6mpg US46.3mpg UK	7.3L/100 km32.2mpg US38.7mpg UK
Fuel consumption city	7.4L/100 km31.8mpg US38.2mpg UK	-
Fuel consumption highway	5.4L/100 km43.6mpg US52.3mpg UK	-
Quarter mile	15.9s Calculated	15.9s Calculated
Power-to-weight	109hp/t81kW/t49hp/1000 lb Calculated	108hp/t80kW/t49hp/1000 lb Calculated
Torque-to-weight	178Nm/t119lb-ft/ton Calculated	175Nm/t117lb-ft/ton Calculated
Estimated range	967km601mi Calculated	836km519mi Calculated
Displacement	1,998cc122cu in	1,998cc122cu in
Length	4,768mm188in	4,708mm185in
Width	1,852mm73in	1,891mm74in
Height	1,384mm54in	1,676mm66in
Wheelbase	2,851mm112in	2,864mm113in
Front track	1,575mm62in	1,620mm64in
Rear track	1,611mm63in	1,636mm64in
Ground clearance	124mm5in	204mm8in
Trunk volume	300L	550L
Max trunk volume	385L	1,600L
Doors	2	5
Seats	4	5
Fuel tank	59L	61L
CO2 emissions	-	166g/km

Performance charts

Use the estimates as comparison hints and verify exact figures before making decisions.

Dyno simulation

Estimated stock-style power and torque curves by engine speed.

BMW 4 Series Convertible (G23) 420iBMW X3 (G01 LCI) Facelift 2021 20iPowerTorque

Dyno simulation data table
Vehicle	Peak power RPM	Peak torque RPM	Max engine speed
BMW4 Series Convertible (G23)420i	5,000-6,500 rpm	1,350-4,000 rpm	6,750 rpm
BMWX3 (G01 LCI)Facelift 202120i	5,000-6,500 rpm	1,350-4,000 rpm	6,750 rpm

Acceleration curve

Estimated speed over time for selected vehicles.

Acceleration and drag-race table
Metric	BMW4 Series Convertible (G23)420i	BMWX3 (G01 LCI)Facelift 202120i
	Acceleration checkpoints
0-60 mph 0-97 km/h	7.8 s	7.7 s
0-100 km/h 0-62 mph	8.2 s	8.2 s
0-200 km/h 0-124 mph	36.3 s	51.5 s
Top speed	236 km/h 147 mph	215 km/h 134 mph
	Drag race simulation
60 ft 18 m	2.6 s	2.5 s
330 ft 101 m	6.9 s	6.7 s
1/8 mile 201 m	10.4 s	10.3 s
1000 ft 305 m	13.4 s	13.4 s
1/4 mile 402 m	15.9 s	15.9 s
Trap speed 1/4 mile 402 m	145 km/h 90 mph	140 km/h 87 mph

Power comparison

Bar comparison chart for Power. Higher is better · hp / kW

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	184 hp 137 kW
BMWX3 (G01 LCI)Facelift 202120i	184 hp 137 kW

Torque comparison

Bar comparison chart for Torque. Higher is better · Nm / lb-ft

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	300 Nm 221 lb-ft
BMWX3 (G01 LCI)Facelift 202120i	300 Nm 221 lb-ft

Curb weight comparison

Bar comparison chart for Curb weight. Lower is better · kg / lb

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	1,690 kg 3,726 lb
BMWX3 (G01 LCI)Facelift 202120i	1,710 kg 3,770 lb

Top speed without limiter comparison

Bar comparison chart for Top speed without limiter. Higher is better · km/h / mph

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	236 km/h 147 mph
BMWX3 (G01 LCI)Facelift 202120i	215 km/h 134 mph

0-100 km/h comparison

Bar comparison chart for 0-100 km/h. Lower is better · seconds

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	8.2 s
BMWX3 (G01 LCI)Facelift 202120i	8.2 s

Fuel consumption comparison

Bar comparison chart for Fuel consumption. Lower is better · L/100 km / mpg US / mpg UK

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	6.1 L/100 km 38.6 mpg US 46.3 mpg UK
BMWX3 (G01 LCI)Facelift 202120i	7.3 L/100 km 32.2 mpg US 38.7 mpg UK

The biggest fuel consumption difference is between BMW 4 Series Convertible (G23) 420i and BMW X3 (G01 LCI) Facelift 2021 20i: 1.2 L/100 km.

Power-to-weight comparison

Bar comparison chart for Power-to-weight. Higher is better · hp/t / kW/t

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	109 hp/t 81 kW/t 9.2 kg/hp
BMWX3 (G01 LCI)Facelift 202120i	108 hp/t 80 kW/t 9.3 kg/hp

Estimated range comparison

Bar comparison chart for Estimated range. Higher is better · km / mi

Chart data table
Vehicle	Value
BMW4 Series Convertible (G23)420i	967 km 601 mi
BMWX3 (G01 LCI)Facelift 202120i	836 km 519 mi

Performance spider chart

Radar chart comparing normalized performance and fuel-consumption scores.

Chart data table
Vehicle	Power	Acceleration	Top speed
BMW4 Series Convertible (G23)420i	184 hp 137 kW	8.2 s	236 km/h 147 mph
BMWX3 (G01 LCI)Facelift 202120i	184 hp 137 kW	8.2 s	215 km/h 134 mph

Most attractive quadrant

Scatter chart with performance score on the X axis and practicality score on the Y axis.

Vehicle

Performance score

Practicality score

BMW4 Series Convertible (G23)420i

Power	184 hp 137 kW
0-100 km/h	8.2 s
Top speed 236 km/h 147 mph

Doors/seats	2 doors 4 seats
Trunk	300 L 10.6 cu ft
Length	4,768 mm 187.7 in
Height	1,384 mm 54.5 in

BMWX3 (G01 LCI)Facelift 202120i

Power	184 hp 137 kW
0-100 km/h	8.2 s
Top speed 215 km/h 134 mph

Doors/seats	5 doors 5 seats
Trunk	550 L 19.4 cu ft
Length	4,708 mm 185.4 in
Height	1,676 mm 66.0 in

Performance vs fuel economy

Cars closer to the top-right corner combine stronger performance with better fuel economy scores.

Vehicle

Performance score

Fuel economy score

BMW4 Series Convertible (G23)420i

Power	184 hp 137 kW
0-100 km/h	8.2 s
Top speed 236 km/h 147 mph

6.1 L/100 km

38.6 mpg US

46.3 mpg UK

BMWX3 (G01 LCI)Facelift 202120i

Power	184 hp 137 kW
0-100 km/h	8.2 s
Top speed 215 km/h 134 mph

7.3 L/100 km

32.2 mpg US

38.7 mpg UK

BMW 4 Series Convertible (G23) 420i is closest to the top-right balance target for performance and fuel economy.

Acceleration vs fuel consumption

Cars closer to the lower-left corner offer a better mix of quick acceleration and low fuel consumption.

Acceleration vs fuel consumption data table
Vehicle	Fuel consumption, L/100 km	0-100 km/h, s
BMW4 Series Convertible (G23)420i	6.1 L/100 km 38.6 mpg US 46.3 mpg UK	8.2 s
BMWX3 (G01 LCI)Facelift 202120i	7.3 L/100 km 32.2 mpg US 38.7 mpg UK	8.2 s

Power-to-weight vs fuel consumption

The shaded area favors higher power-to-weight with lower combined fuel consumption.

Power-to-weight vs fuel consumption data table
Vehicle	Power-to-weight, hp/t	Fuel consumption, L/100 km
BMW4 Series Convertible (G23)420i	109 hp/t 81 kW/t 9.2 kg/hp	6.1 L/100 km 38.6 mpg US 46.3 mpg UK
BMWX3 (G01 LCI)Facelift 202120i	108 hp/t 80 kW/t 9.3 kg/hp	7.3 L/100 km 32.2 mpg US 38.7 mpg UK

Detailed score breakdown

Vehicle

BMW4 Series Convertible (G23)420i

BMWX3 (G01 LCI)Facelift 202120i

Power

184 hp

137 kW

184 hp

137 kW

Torque

300 Nm

221 lb-ft

300 Nm

221 lb-ft

Acceleration

8.2 s

Top speed

236 km/h

147 mph

215 km/h

134 mph

Lightness

1,690 kg

3,726 lb

1,710 kg

3,770 lb

Fuel consumption

6.1 L/100 km

38.6 mpg US

46.3 mpg UK

7.3 L/100 km

32.2 mpg US

38.7 mpg UK

Practicality

Doors/seats	2 doors 4 seats
Trunk	300 L 10.6 cu ft
Length	4,768 mm 187.7 in
Height	1,384 mm 54.5 in

Doors/seats	5 doors 5 seats
Trunk	550 L 19.4 cu ft
Length	4,708 mm 185.4 in
Height	1,676 mm 66.0 in

Range score

967 km

601 mi

836 km

519 mi

CO2 score

166 g/km

Trunk score

300 L

10.6 cu ft

550 L

19.4 cu ft

Power-to-weight score

109 hp/t

81 kW/t

9.2 kg/hp

108 hp/t

80 kW/t

9.3 kg/hp

Overall

Fixed score

Fuel cost and annual usage

Estimate running costs from combined consumption, your annual distance, and the fuel price in your local currency.

Average annual distanceDistance unitFuel price in your local currencyPrice unit

Enter the fuel price in your local currency, for example €/L, $/gal, £/L or any other local currency.

LC = Local Currency

Fuel cost and annual usage
Vehicle	BMW 4 Series Convertible (G23) 420i	BMW X3 (G01 LCI) Facelift 2021 20i
Consumption	6.1 L/100 km38.6 mpg US46.3 mpg UK	7.3 L/100 km32.2 mpg US38.7 mpg UK
Cost / 100 km	10.67 LC100 km	12.78 LC100 km
Cost / 100 mi	17.18 LC100 mi	20.56 LC100 mi
Annual fuel used	915 L242 US gal201 UK gal	1,095 L289 US gal241 UK gal
Annual fuel cost	1,601 LC/year	1,916 LC/year