General Motors

General Motors Corp., in an effort to increase the performance of its midsize trucks and the Hummer H3 SUV, is jacking up the displacement and power of its Vortec series of inline 4- and 5-cyl. powerplants. The improvements, which first were applied last year to the Vortec 4200 4.2L inline 6-cyl., are part of GM's recent investment in its Powertrain Div. for 19 new or significantly revised engines