The Sierra and its Chevy Silverado twin were redesigned and much improved for 1999. Engines are smaller but more powerful and economical, and the interior feels spacious. Braking and handling are also better. Four-door extended-cab versions are the only extended-cab pickups with decent rear seats. Four-wheel-drive models offer an Autotrac system that can remain engaged all the time. The new C3 model is a luxurious all-wheel-drive version with a 325-hp, 6.0-liter V8. Extended-cab models get top-tether child anchors in back for 2001.