People should tip limousine drivers between 15 and 20 percent. That range is typically advised for service received from professional staff in most industries, and it applies equally to limousine and town car drivers.
If the service a person receives from a chauffeur isn't outstanding and is just average, a 15 percent gratuity wouldn't be out of the question. However, if the driver provides service that goes above and beyond the average, then paying a little extra, for example, 20 percent or higher, is appropriate.
Tipping is not mandatory. A service charge that a chauffeured transportation company might impose on a customers is not the tip.