Automakers are planning to introduce as many as two dozen small sport-utility-like vehicles with car-based designs in the coming years and ask that they be classified as light trucks, a designation that has lower fuel-efficiency requirements. The new designs look like hybrids of SUVs, minivans, and cars. While the new vehicles get worse gas mileage than many cars, they get better gas mileage than most light trucks, so they will help automakers keep the average mileage for their light-truck fleets down, thereby letting them sell more of their big, high-profit, less-efficient SUVs. The Senate is expected today to extend a four-year-old ban that prevents the Clinton administration from changing 20-year-old fuel economy standards that allow light trucks to get away with significantly lower fuel economy than cars. The House has already approved an extension.