was enlarged (adding larger windows, moving the firewall forward). In 2001, International introduced the "NGV" trucks (Next Generation Vehicles); the first model family developed under the founding of Navistar, NGV was intended as the successor of the Thousand-Series trucks (though using a nearly identical nomenclature). The S-Series lasted in production through 2003 for severe-service trucks and 2004 as a cowled bus chassis. In 2002, AmTran was rebranded as IC (Integrated Coach) after a few months as International Truck and Bus. For 2004, Navistar reentered the consumer vehicle market for the first time since 1980, introducing the International XT (Extreme Truck) model family. Three pickup trucks were sold, including the CXT 4x4 (derived from the 7300), the RXT 4x2 (derived from the 4300) and the MXT 4x4 (a MXT-MV redeveloped for street-legal use). The CXT and RXT are (by far) the largest vehicles ever sold for consumer sale; to date, the former is the tallest ever mass-produced and the latter is the longest pickup truck ever mass-produced. Following the 2006 introduction of the International ProStar long-haul tractor (replacing the aerodynamic 9400i), International began to retire its previous "Thousand-Series" nomenclature for NGV-based trucks. In 2008, the medium-duty 4000 became the DuraStar with the 7000 severe-service trucks becoming the WorkStar. The 8000 regional-haul tractors revived the TranStar name; the LoneStar flagship long-haul tractor had no predecessor. Using the previous-generation i-series cab, the Paystar 5000 and the 9000i (pared down to the 9900i) In response to low market demand, International ended sales of all three XT pickup truck lines after the 2008 model year. Purchase of Workhorse In 2005, Navistar purchased the Workhorse Custom Chassis, LLC (started in 1998 by investors who took over production and sales of General Motors' popular P-series Stepvan chassis when GM dropped it), a manufacturer of step-van and motor home chassis, to seemingly re-enter the delivery van market. It appeared that the new subsidiary might also benefit by its association with a company whose history from the 1930s into the '60s included the popular Metro van. For a short time Workhorse offered an integrated chassis-body product called MetroStar. In Sept. of 2012, Navistar announced the shut down of Workhorse and the closure of the plant in Union City, Indiana, in order to cut costs. In March 2013, AMP Electric Vehicles took over Workhorse Custom Chassis, LLC's assets and began offering a range of electric vehicles. In 2015, AMP changed