After the parade of electric and plug-in-hybrid vehicles introduced at this year's Detroit auto show, a few questions remain: Do consumers really want plug-in cars, are they willing to pay significantly more to get them, and do they have the patience to wait for the first massproduced ones to hit the market?In December, sales of hybrid cars fell even further than those of gas-powered cars, suggesting that slumping consumer confidence has overtaken a fear of fuel prices in the race to sway car shoppers. Yet early word on pricing for plug-in cars suggests they'll cost significantly more than hybrids and regular gas-powered cars.