First, if anyone else tries to get in the cab you are travelling in, GET OUT first thing! Refuse to let another member get inside your cab and call for help.
Second, take the usual precaution of informing your near and dears one about your location and send them a tracker, so they exactly where you are throughout the journey.
Third, call your family or friends frequently and tell them your location, so that the driver is well aware that there are other people who know of your whereabouts.
Fourth, ask the driver to take only main roads and go via crowded places even if it means taking a long route. Avoid shortcuts and dingy spots.
Fifth, keep your defenses up. Always be aware and alert of your surroundings. Learn a few self defense techniques, you never know when you might need them!