These numbers are quite interesting, and the sales growth patterns are very parallel. One factor that is going to make a major difference, however, is that the Prius didn't have real competition. The Volt does. The next few years should be fun.
Off and on, sure, but the problem with gasoline prices were the volatility, even when the Prius was first selling. I remember gas being $0.90 a gallon one year and $2.00 a gallon the next. Most people I knew complained about the shift in price more so than anything else. They didn't really start complaining about the overall price of gas until it consistently hit $4.00 a gallon.The Prius had a different kind of competition: cheap gas.
I would hardly consider the first generation Insight as competition for the Prius, though it was superior as a commuter car in almost every measurable way. It simply wasn't a car that most people could live with. Despite the Prius's anemic performance and cheap interior/amenities, it could still seat five people and carry an appreciable amount of cargo. The Insight really was purely a commuter car and nothing more.The Prius did have competition - The Honda Insight.