I have used taxis and other transportation services extensively both domestically and abroad due to my work that has me travel quite often. In the course of these travels I have learned a few tricks regarding how to most safely use such transportation services.
Verify the Car is Legitimate
My suggestion is to be sure that you use a marked taxi rather than other car services. Now with Uber and Lift these solutions can also be used with at least some level of verification that the driver is legitimate. I recommend that you avoid private car services, especially if they are a service that you did not specifically call. I see this happen at airports routinely. When exiting an airport to hail a cab I have been approached by individuals who offer their own car service. These people could, of course, be anyone. While there is no guarantee that a cab driver is a safe bet there is at least more guarantee when using a dedicated taxi service.
I suggest making a mental note of the cab number when you get in the car so that you have that information if you need it in the future. You can, of course, snap a picture of the cab number and license plate with your phone as well. This will allow you to better identify the car if anything does happen that you need to report to authorities. On a lighter note, this is also very helpful information to have if you forget something in the cab!
Keep Your Most Essential Belongings with You
Don’t put your most essential items in the trunk. Keep your carry bag, which should have your really important items such as money, passport and IDs, on your person, or keep these essentials actually in your pockets. This way, if something happens and you must flee the cab you will have at least these items with you. It also serves well if the cab is stopped by authorities and you need to provide ID of any kind.
Especially if traveling internationally I like to keep my most important documents and belongings on my person. In the event of an emergency this is the only strategy that will ensure, for the most part, that you have possession of these items. If something happens while in a cab or other transportation vehicle it will be very helpful to local authorities and to yourself if you are able to provide your passport and other identification. You may have lost your clothing that was in a luggage bag in the trunk, but at least you won’t be stranded with no passport, money, and means to get home.
Position Yourself for Action
Typically as a passenger you will sit in the back seat. If I get in a car with a driver that makes me uncomfortable I personally like to sit directly behind him. The driver of a car is actually in a vulnerable position to a passenger directly to the rear. If you had to you could use this to your advantage. If a driver deliberately drives past you destination and does not respond to your protest this is a sign things are bad and you may have no choice but to use force if this is the case. Even if you must take action and it causes a crash, doing so if the cab is moving slowly may be the better option than allowing the driver to get you to his planned destination.
When initially sitting in the cab I like to close the door, then immediately re-open and close it again. This will appear as nothing more than your suspicion that the door did not properly close. In reality, this verifies that there is not a child safety lock or some other mechanism turned on that will trap you in the car. Unless somehow modified, the regular car locks should be accessible to you at the rear car doors to unlock if needed but a child safety lock would trap you in. Better to know that before departing than have to deal with the situation later. If you must make a quick exit from the vehicle do so on the passenger side so that you have a better start ahead of the driver who will have the vehicle as an obstacle when he initially gets out on his side.
I suggest not getting into cabs or other car services alone if you are compromised in any way. If you have had too much to drink a taxi ride home is much better than driving but you should plan ahead so that you have a ride with someone you trust or have someone you trust with you when using a transportation service. A drunk customer makes for an easy mark for any driver who is up to no good.
Know the Route
Try to have some semblance of the route to where you are going. If traveling domestically or in a developed country you may have the option to look up the route via GPS on your phone. If you determine that the driver is taking you somewhere other than your destination then it is time to act. If you demand an explanation for the variance in the route and get a concerning response, or are simply ignored, you may need to escape the car. If the vehicle is moving slowly enough or comes to a halt at any point you can make your move to bolt, again, a good reason to be wearing your bag with the most essential belongings.
Often it is understood that the drive will take you on the route you want to go. Be cautious if the driver suggests alternate routes that would take you through back neighborhoods or into out-of-the-way locations. Even if it means spending a few more minutes in traffic a malicious driver has far fewer opportunities to do anything criminal when sitting in the middle of busy highways compared to driving down back allys.
Discuss Rate and Payment before Departing
It is always best practice to specify rate and method of payment before getting in the car. Domestically all proper taxis should be marked with rate information. It is still good, however, to verify with the driver that he accepts your method of payment (certain credit card types, for example) before getting in the car.
When traveling in third-world countries be aware that corruption tends to be far more rampant in every aspect of society and cab drivers can be among the worst. Be sure to have enough cash on you to pay for the ride and be sure to carry small enough bills. You may not get your change back without issues under such circumstances.