"Black and Latino passengers also demonstrated biased tipping in favor of white drivers. Black passengers tipped white drivers 48 percent more than Black drivers, while white passengers tipped white drivers 49 percent more than Black drivers. Latino passengers had the most disparate tipping, giving white drivers a 146 percent higher tip than Black drivers, which supports previous studies' findings that Latinos tend to identify more with whites than Blacks."
Here's the article: http://www.diversityinc.com/public/3277.cfm?gclid=CPnxjqzXkJQCFSoZa...