General Motors said on Monday that, in an attempt to boost sales, it would waive up to six months of lease payments on most GM models if the owners buy or lease a new vehicle, according to Reuters. GM will nullify lease payments on contracts that expire between July 1 and January 2, 2004, if the owners buy or lease any new GM vehicle except a Saab, Hummer or medium-duty truck, GM spokeswoman Elaine Redd told the news agency.