On November 8, 2004, the Chicago Transit Board approved the purchase of a base order of 265 new model D40LF buses from New Flyer of America, Inc. The purchase included 20 model DE40LF diesel-electric hybrids, as well as options for the purchase of up to 1,030 additional diesel buses.
The CTA began accepting delivery of the base order in February 2006. On May 10, 2006, the Chicago Transit Board approved the purchase of an additional 185 buses, exercising the first of four options for additional buses. A second option for 200 additional buses was exercised on November 8, 2006. The final two options, for 400 buses, was exercised on May 17, 2007.
The exterior of the new buses is nearly identical to the existing 5800-series D40LFs. Inside, the buses feature strap hangers and an easy-touch rear door. The buses also have all the standard CTA amenities, including air conditioning, security cameras, bike racks, automated announcement systems, and wheelchair ramps.