MADISON, Wis. --- The nation's first major hybrid vehicle show, dubbed "Hybridfest," is expected to attract thousands to the Alliant Energy Center in Madison this weekend. The event will include demonstrations of plug-in hybrid technology. Exhibitors will include Hymotion of Canada, a company developing a plug-in kit for hybrids, according to a report from the Capital Times. Such kits are expected to allow Prius owners to upgrade their vehicle, although a professional mechanic will need to make the conversion. The problem is, however, the plug-in kit conversion will cost $10,000 to $12,000 to make, and the extra hardware will slow down vehicle performance, a local Toyota dealer told the newspaper. However, this month Toyota announced plans to pursue plug-in hybrid technology. During a speech this week at the National Press Club, Jim Press, president of Toyota's North American subsidiary, said the future hybrid plug-in Toyota will travel greater distances without using its gas engine, better conserve oil, and "slice smog and greenhouse gases to nearly imperceptible levels." According to the Capital News, Press added that Toyota's hybrid technology has staying power because it can adapt to a number of alternatives, including clean diesels, biodiesels, ethanol, plug-in hybrids and hydrogen fuel cells. Hybridfest will feature more than 100 hybrid cars. Details are available at www.hybridfest.com. Test drives will be available.