Polk says that part of the reason that as many as a third of current hybrid owners say they would not buy a hybrid for their next car is that higher fuel prices had not fed through when the data was collected. They might be right - Chevrolet, which last month suspended production of the Volt because it was making more than it could sell, yesterday reported the best sales ever for the product - due, it says, to higher fuel prices making customers more aware of the cost of filling up.

The Polk research found that brand loyalty was more prevalent than loyalty to the green concept. It says "Hybrid owners appear to maintain brand loyalty when returning to the new car market. For example, in 2011, 60 percent of Toyota hybrid owners returned to the market to purchase another Toyota, according to Polk, while 41 percent of them purchased another hybrid from any brand. In the case of Honda hybrid owners, more than 52 percent of them stayed with the Honda brand, while just under 20 percent of this same owner group bought another hybrid vehicle from any brand."

Hybrid vehicles represent just 2.4 percent of the overall new vehicle market in the U.S., according to Polk, down from a high of 2.9 percent in 2008.

Polk's research also indicates that volatility in fuel prices between 2008 and 2011, which ranged from just under USD2.00/gallon to nearly USD4.00/gallon, had little impact on hybrid segment loyalty. As fuel prices continue to rise, Polk will be working closely with its customers to continue to analyse the impact.