A power pack for a vehicle, comprising: an internal combustion engine comprising: a crankcase; a crankshaft disposed in the crankcase; and a cylinder body connected to the crankcase; a continuous variable transmission operatively connected to the engine, the continuous variable transmission comprising: a drive pulley operatively connected to the crankshaft of the engine, the drive pulley being rotatable about a drive pulley axis; a driven pulley rotatable about a driven pulley axis; a belt connecting the drive pulley to the driven pulley; and a housing at least partly enclosing the drive pulley, the driven pulley and the belt; an electric motor module operatively connected to the continuous variable transmission, the electric motor module comprising: an electric motor having a motor shaft rotatable about a motor shaft axis; a gearing assembly operatively connected to the motor shaft; and a drive connection shaft operatively connected between the driven pulley of the continuous variable transmission and the gearing assembly, the motor shaft being selectively operable to drive the drive connection shaft via the gearing assembly; and a sub-transmission (110, 210, 310) operatively connected to the drive connection shaft of the electric motor module, the sub-transmission comprising an output shaft (120, 220, 320) configured to be operatively connected to at least one ground-engaging member of the vehicle, characterized in that the motor shaft being selectively operable to be driven by the drive connection shaft via the gearing assembly. an internal combustion engine comprising: a crankcase; a crankshaft disposed in the crankcase; and a cylinder body connected to the crankcase; a crankcase; a crankshaft disposed in the crankcase; and a cylinder body connected to the crankcase; a continuous variable transmission operatively connected to the engine, the continuous variable transmission comprising: a drive pulley operatively connected to the crankshaft of the engine, the drive pulley being rotatable about a drive pulley axis; a driven pulley rotatable about a driven pulley axis; a belt connecting the drive pulley to the driven pulley; and a housing at least partly enclosing the drive pulley, the driven pulley and the belt; an electric motor module operatively connected to the continuous variable transmission, the electric motor module comprising: an electric motor having a motor shaft rotatable about a motor shaft axis; a gearing assembly operatively connected to the motor shaft; and a drive connection shaft operatively connected between the driven pulley of the continuous variable transmission and the gearing assembly, the motor shaft being selectively operable to drive the drive connection shaft via the gearing assembly; and an electric motor having a motor shaft rotatable about a motor shaft axis; a gearing assembly operatively connected to the motor shaft; and a drive connection shaft operatively connected between the driven pulley of the continuous variable transmission and the gearing assembly, the motor shaft being selectively operable to drive the drive connection shaft via the gearing assembly; and a sub-transmission (110, 210, 310) operatively connected to the drive connection shaft of the electric motor module, the sub-transmission comprising an output shaft (120, 220, 320) configured to be operatively connected to at least one ground-engaging member of the vehicle, characterized in that the motor shaft being selectively operable to be driven by the drive connection shaft via the gearing assembly.