Mercedes-Benz R-Class 2006 Owners Manual - Manual (Page 519)

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Technical data
Electrical system
Model R 350 R 500
Generator (alternator) 14 V /150 A 14 V /180 A
Starter motor 12 V /1.4 kW 12 V /1.7 kW
Battery 12 V/70 Ah 2 V/95 Ah
Spark plugs NGK PLKR 6A NGK PFR 5R-11
Electrode gap 0.031 in (0.8 mm) 0.031 in (0.8 mm)
Tightening torque 15 - 22 lb-ft (20 - 30 Nm) 15 - 22 lb-ft (20 - 30 Nm)