Car comparison

BMW 6 Series (E63) 645CivsBMW 8 Series (E31) 850Csi 5.6

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

New comparison

BMW 6 Series (E63)

645Ci

333 hp4398 ccGasolineRWDAutomaticNaturally aspiratedCoupe2003-2005
VS

BMW 8 Series (E31)

850Csi 5.6

380 hp5576 ccGasolineRWDManualNaturally aspiratedCoupe1992-1996

Comparison overview

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

Best choices

BMW 6 Series (E63) 645Ci

  • Quickest 0-100 km/h
    5.8 s
  • Fastest top speed
    265 km/h
    165 mph Unrestricted
    250 km/h
    155 mph Restricted
  • Lightest
    1,695 kg
    3,737 lb
  • Lowest combined fuel consumption
    10.9 L/100 km
    21.6 mpg US
    25.9 mpg UK
  • Largest trunk
    450 L
  • Best overall score
    63/100
  • Best economy score
    78/100
  • Best practicality score
    53/100

BMW 8 Series (E31) 850Csi 5.6

  • Most powerful
    380 hp
    283 kW
  • Highest torque
    550 Nm
    406 lb-ft
  • Best power-to-weight
    200 hp/t
    149 kW/t
    5.0 kg/hp
  • Best estimated range
    703 km
    437 mi
  • Best performance score
    70/100

Specification comparison

Specification comparison
ModelBMW6 Series (E63)645CiBMW8 Series (E31)850Csi 5.6
Power
333hp248kW
380hp283kW
Torque
450Nm332lb-ft
550Nm406lb-ft
Curb weight
1,695kg3,737lb
1,900kg4,189lb
Gross weight
2,065kg4,553lb
2,340kg5,159lb
Top speed
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Calculated
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Calculated
To 99% top speed
79.6s99% target: 262 km/h / 163 mph
Calculated
83.2s99% target: 262 km/h / 163 mph
Calculated
0-100 km/h
5.8s
6.0s
0-200 km/h
20.3s
Calculated
21.1s
Calculated
0-60 mph
5.5s
Calculated
5.7s
Calculated
Fuel consumption
10.9L/100 km21.6mpg US25.9mpg UK
12.8L/100 km18.4mpg US22.1mpg UK
Fuel consumption city
16.1L/100 km14.6mpg US17.5mpg UK
-
Fuel consumption highway
8L/100 km29.4mpg US35.3mpg UK
-
Quarter mile
13.9s
Calculated
14.1s
Calculated
Power-to-weight
196hp/t147kW/t89hp/1000 lb
Calculated
200hp/t149kW/t91hp/1000 lb
Calculated
Torque-to-weight
265Nm/t178lb-ft/ton
Calculated
289Nm/t194lb-ft/ton
Calculated
Estimated range
642km399mi
Calculated
703km437mi
Calculated
Displacement
4,398cc268cu in
5,576cc340cu in
Length
4,820mm190in
4,780mm188in
Width
1,855mm73in
1,855mm73in
Height
1,373mm54in
1,330mm52in
Wheelbase
2,780mm109in
2,684mm106in
Front track
1,558mm61in
1,554mm61in
Rear track
1,592mm63in
1,562mm61in
Trunk volume
450L
320L
Doors
2
2
Seats
4
4
Fuel tank
70L
90L
CO2 emissions
264g/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 6 Series (E63) 645CiBMW 8 Series (E31) 850Csi 5.6PowerTorque
  • BMW 6 Series (E63) 645Ci: Power / Torque
  • BMW 8 Series (E31) 850Csi 5.6: Power / Torque
Dyno simulation data table
VehiclePeak power RPMPeak torque RPMMax engine speed
BMW6 Series (E63)645Ci6,100 rpm3,600 rpm6,350 rpm
BMW8 Series (E31)850Csi 5.65,300 rpm4,000 rpm5,550 rpm

Acceleration curve

Estimated speed over time for selected vehicles.

Acceleration and drag-race table
MetricBMW6 Series (E63)645CiBMW8 Series (E31)850Csi 5.6
Acceleration checkpoints
0-60 mph
0-97 km/h
5.5 s
5.7 s
0-100 km/h
0-62 mph
5.8 s
6.0 s
0-200 km/h
0-124 mph
20.3 s
21.1 s
Top speed
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Likely limited
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Likely limited
Drag race simulation
60 ft
18 m
2.3 s
2.4 s
330 ft
101 m
6.1 s
6.2 s
1/8 mile
201 m
9.1 s
9.2 s
1000 ft
305 m
11.7 s
11.9 s
1/4 mile
402 m
13.9 s
14.1 s
Trap speed
1/4 mile
402 m
169 km/h
105 mph
167 km/h
103 mph

Power comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci
333 hp
248 kW
BMW8 Series (E31)850Csi 5.6
380 hp
283 kW

BMW 8 Series (E31) 850Csi 5.6 has 47 hp more than BMW 6 Series (E63) 645Ci.

The biggest power difference is between BMW 6 Series (E63) 645Ci and BMW 8 Series (E31) 850Csi 5.6: 47 hp (35 kW).

Torque comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci
450 Nm
332 lb-ft
BMW8 Series (E31)850Csi 5.6
550 Nm
406 lb-ft

Curb weight comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci
1,695 kg
3,737 lb
BMW8 Series (E31)850Csi 5.6
1,900 kg
4,189 lb

Top speed without limiter comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
BMW8 Series (E31)850Csi 5.6
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph

0-100 km/h comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci5.8 s
BMW8 Series (E31)850Csi 5.66.0 s

Although BMW 8 Series (E31) 850Csi 5.6 has more power, BMW 6 Series (E63) 645Ci is quicker from 0-100 km/h.

The biggest 0-100 km/h difference is between BMW 6 Series (E63) 645Ci and BMW 8 Series (E31) 850Csi 5.6: 0.2 s.

Fuel consumption comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci
10.9 L/100 km
21.6 mpg US
25.9 mpg UK
BMW8 Series (E31)850Csi 5.6
12.8 L/100 km
18.4 mpg US
22.1 mpg UK

The biggest fuel consumption difference is between BMW 6 Series (E63) 645Ci and BMW 8 Series (E31) 850Csi 5.6: 1.9 L/100 km.

Power-to-weight comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci
196 hp/t
147 kW/t
5.1 kg/hp
BMW8 Series (E31)850Csi 5.6
200 hp/t
149 kW/t
5.0 kg/hp

Estimated range comparison

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

Chart data table
VehicleValue
BMW6 Series (E63)645Ci
642 km
399 mi
BMW8 Series (E31)850Csi 5.6
703 km
437 mi

Performance spider chart

Radar chart comparing normalized performance and fuel-consumption scores.

Chart data table
VehiclePowerAccelerationTop speed
BMW6 Series (E63)645Ci
333 hp
248 kW
5.8 s
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
BMW8 Series (E31)850Csi 5.6
380 hp
283 kW
6.0 s
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph

Most attractive quadrant

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

Chart data table
VehiclePerformance scorePracticality score
BMW6 Series (E63)645Ci
Power
333 hp
248 kW
0-100 km/h5.8 s
Top speed
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Doors/seats
2 doors
4 seats
Trunk
450 L
15.9 cu ft
Length
4,820 mm
189.8 in
Height
1,373 mm
54.1 in
BMW8 Series (E31)850Csi 5.6
Power
380 hp
283 kW
0-100 km/h6.0 s
Top speed
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Doors/seats
2 doors
4 seats
Trunk
320 L
11.3 cu ft
Length
4,780 mm
188.2 in
Height
1,330 mm
52.4 in

Performance vs fuel economy

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

Performance vs fuel economy data table
VehiclePerformance scoreFuel economy score
BMW6 Series (E63)645Ci
Power
333 hp
248 kW
0-100 km/h5.8 s
Top speed
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
10.9 L/100 km
21.6 mpg US
25.9 mpg UK
BMW8 Series (E31)850Csi 5.6
Power
380 hp
283 kW
0-100 km/h6.0 s
Top speed
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
12.8 L/100 km
18.4 mpg US
22.1 mpg UK

BMW 6 Series (E63) 645Ci 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
VehicleFuel consumption, L/100 km0-100 km/h, s
BMW6 Series (E63)645Ci
10.9 L/100 km
21.6 mpg US
25.9 mpg UK
5.8 s
BMW8 Series (E31)850Csi 5.6
12.8 L/100 km
18.4 mpg US
22.1 mpg UK
6.0 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
VehiclePower-to-weight, hp/tFuel consumption, L/100 km
BMW6 Series (E63)645Ci
196 hp/t
147 kW/t
5.1 kg/hp
10.9 L/100 km
21.6 mpg US
25.9 mpg UK
BMW8 Series (E31)850Csi 5.6
200 hp/t
149 kW/t
5.0 kg/hp
12.8 L/100 km
18.4 mpg US
22.1 mpg UK

Detailed score breakdown

Detailed score breakdown
VehicleBMW6 Series (E63)645CiBMW8 Series (E31)850Csi 5.6
Power
333 hp
248 kW
380 hp
283 kW
Torque
450 Nm
332 lb-ft
550 Nm
406 lb-ft
Acceleration
5.8 s
6.0 s
Top speed
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Unrestricted
265 km/h165 mph
Restricted
250 km/h155 mph
Lightness
1,695 kg
3,737 lb
1,900 kg
4,189 lb
Fuel consumption
10.9 L/100 km
21.6 mpg US
25.9 mpg UK
12.8 L/100 km
18.4 mpg US
22.1 mpg UK
Practicality
Doors/seats
2 doors
4 seats
Trunk
450 L
15.9 cu ft
Length
4,820 mm
189.8 in
Height
1,373 mm
54.1 in
Doors/seats
2 doors
4 seats
Trunk
320 L
11.3 cu ft
Length
4,780 mm
188.2 in
Height
1,330 mm
52.4 in
Range score
642 km
399 mi
703 km
437 mi
CO2 score
264 g/km
-
Trunk score
450 L
15.9 cu ft
320 L
11.3 cu ft
Power-to-weight score
196 hp/t
147 kW/t
5.1 kg/hp
200 hp/t
149 kW/t
5.0 kg/hp
Overall
Fixed score
Fixed score

Fuel cost and annual usage

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

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
VehicleBMW 6 Series (E63) 645CiBMW 8 Series (E31) 850Csi 5.6
Consumption10.9 L/100 km21.6 mpg US25.9 mpg UK12.8 L/100 km18.4 mpg US22.1 mpg UK
Cost / 100 km19.08 LC100 km22.40 LC100 km
Cost / 100 mi30.70 LC100 mi36.05 LC100 mi
Annual fuel used1,635 L432 US gal360 UK gal1,920 L507 US gal422 UK gal
Annual fuel cost2,861 LC/year3,360 LC/year

Head-to-head comparisons

BMW 6 Series (E63) 645Ci

  • Is 205 kg lighter
  • Is 0.2 s quicker from 0-100 km/h
  • Uses 1.9 L/100 km less fuel
  • Has 130 L more trunk volume

Pros

  • Quickest 0-100 km/h in this comparison
  • Highest top speed
  • Lightest
  • Lowest combined fuel consumption
  • Largest trunk

Cons

  • Lowest power

BMW 8 Series (E31) 850Csi 5.6

  • Has 47 hp more
  • Has 100 Nm more
  • Has 4 hp/t better power-to-weight
  • Has 61 km (38 mi) more estimated range

Pros

  • Most powerful
  • Highest torque
  • Best power-to-weight ratio
  • Best estimated range

Cons

  • Slowest 0-100 km/h
  • Highest combined fuel consumption
  • Heaviest
  • Smallest trunk

Choose cars to compare

Brand
Model
Generation
Engine or modification
BMW 6 Series (E63) 645Ci
BMW 8 Series (E31) 850Csi 5.6
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