Abstract: A device, lockable onto the rim of a vehicle steering wheel, includes a portion in the form of a bar (1) projecting away from the wheel to obstruct steering. The device has a hook member (2) shaped to extend from one end to the other of a segment of a steering wheel rim via a path passing through the wheel with the member hooked over the wheel rim at one end of the segment. The device has a catch (10) movable relative to the hook member (2) and engageable with the steering wheel rim for locking the device to the wheel so that the hook member (2) is engaged about the rim at one end of the segment and the shank (3) of the hook member (2) is secured against the wheel rim at the other end of the segment.