Save On Certified Pre-owned Cars In LOWELL - Used cars can save you money on the purchase price, but they could cost you more for maintenance. If you prefer peace of mind in a used vehicle purchase, a Buick and GMC certified pre-owned vehicle can offer you that. The certified used vehicles at Greater Lowell Buick GMC must complete an extensive multi-point check by certified mechanics. Our CPO cars also come with warranties. To put it simply, our CPO vehicles are in their own category. They are not used or new. They are like-new cars. You get the latest design, comfort, and superior quality at a lower price tag.