Tipping an individual for any rendered service meant to show appreciation. Before, it is an optional bonus allotted at the judgment of the individual paying for the service. Tipping, in recent years, has been a mandatory obligation, regardless of the service that has been rendered.
When getting a limo as car service, tipping the chauffeur would depend on a number of factors. Some limousine companies would have a mandatory tip of 15-20% included in the price of the limo rental, even if you have hired the limo for a short period of time. Although this may appear to be unfair, the fee would actually compensate and protect the limo chauffeur.