The portable electronic device (1) allows functions and/or data of a vehicle to be controlled and managed. In order to do this, the portable device comprises, in a casing having an upper part (10) fixed, for example, in a removable manner on a lower part (11), means for wirelessly transmitting and receiving signals for short range personalised communication with the vehicle. It further comprises a microprocessor unit for processing functions and/or data of the device and of the vehicle, at least one display screen (3) having a portion which is visible from outside the casing for displaying different menus or data of the device or of the vehicle, and manual control means (5, 6) for controlling the execution of functions of the microprocessor unit. A power source, such as a battery, is provided in the casing for supplying electric power to all the electronic components of the device. The manual control means comprise control keys (5) each having a touch-sensitive pad arranged on an inner face of the upper part (10) of the casing. Each control key may be individually activated by a finger of a user placed on the casing in a specified region of the touch-sensitive pad to be activated. The control means further comprise at least one control button (6) which can be pressed, in particular to make the control keys (5) and the display screen (3) switch from an idle mode to an operating mode.