If we based our understanding of this shift in the global auto market (GM's been in the lead for decades) on the news we read here on AutoblogGreen, then it'd be tempting to say it's because of Toyota's longstanding focus on emissions and fuel economy that's helped them move to the top of the leader board. The New York Times seems to agree, saying today that Toyota has "built a reputation for technological leadership as well, most notably with the Prius and other hybrid cars," which contributed to their gains. But an auto analyst interviewed on the BBC show The World (Jay Nagley) said this morning that Toyota's green image is mostly a US thing. Their production of quality cars, though, and the company's resulting popularity is a global phenomenon.
[Source: BBC, New York Times]