As contractors are shaking loose from the recession, General Motors is filling dealers' lots with redesigned, light-duty pickups that are arguably its best ever, offering up to 24 miles per gallon on the highway, a 12,000-lb towing capacity and a payload rating of 2,108 lb. With enhanced details, including a standard two-year, 24,000-mile free maintenance plan, GM's 36-month residual values are estimated to rise five to 10 percentage points higher than outgoing 2013 models, according to research firm ALG.