Google is building a fleet of electric-powered self-driving cars that it plans to begin testing by the end of the year. The technology giant plans to test the compact two-seat vehicles with safety drivers, Google co-founder Sergey Brin said in an interview on Tuesday night. Brin says the cars are part of Google’s effort to re-engineer transportation. “What I’m excited about is how we could change transportation today,” Brin said. “If you look at people who are too old, too young, or disabled, and can’t get around, that’s a big challenge for them.”