To upgrade fuel economy, the Thousand-Series trucks received an aerodynamic hood with faired in headlamps and turn signals; a body-color grille replaced chrome trim.

In 1990, International introduced the 9400, an aerodynamic Class 8 truck derived from the Transtar/Paystar cab, using a set-back front axle (to allow for a longer, sloped hood); the classic-style 9300 (the previous Transtar) continued.

Serving as a chassis supplier since the 1920s, Navistar gained significant market share in school bus production, acquiring AmTran entirely in April 1995.

Sharing only displacement with its predecessor, the T444E introduced direct injection and standard turbocharging; the engine marked the introduction of the PowerStroke diesel branding for Ford vehicles.

[8] After nearly a century of business in Chicago, Navistar announced its plans on 30 September 2000 to leave the city and relocate its corporate offices to west suburban Warrenville, Illinois.

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.

[24] On September 9, 2012, billionaire and key stock holder Carl Icahn sent an open letter to Navistar's board, blasting them for "abysmal business decisions" and "poor corporate governance."

Icahn noted from 2009 to 2012, that "this Board has authorized spending shareholder money on lawsuits against suppliers, competitors and regulators, marketing plans to convince customers that non-compliant engines are actually compliant, accumulating non-core assets such as a Recreational Vehicle manufacturer, and a "gold-plated" corporate headquarters that cost over $100 million.

[35] On July 31, 2015, Navistar ceased operations and laid off the remaining 15 employees at the Truck Development and Technology Center (TDTC) in Fort Wayne, Indiana.

[20] In November 2015 and December 2015, several hundred Navistar employees voluntarily left the Corporate HQ office in Lisle, IL, as part of another Voluntary Separation Package (VSP).

[36] Interim CEO Lewis Campbell's priorities included a focus on quality, reducing the company's cost structure and paring back its product line.

"[40] In January 2014, Forbes reported several key challenges facing Navistar, which include declining military sales, a pension plan underfunded by $2.7 billion, two self-disclosed weaknesses in accounting practices and a new collective bargaining agreement for the company's 6,000 full and part-time workers who are represented by labor unions.

The future trucks will be jointly developed using Navistar's expertise in rolling chassis configurations and manufacturing capabilities, and GM's commercial components and engines.

[48] In April 2021, Navistar International Corp. and Traton SE's pending merger transaction began its review process with Brazil's Administrative Council for Economic Defense, or CADE, with market surveys being distributed to 35 companies.

In 1991, parent company Navistar expanded its presence in the segment as it acquired a stake in school bus body manufacturer AmTran, completing its purchase in 1995.

The IC Bus name stands for Integrated Coach, denoting how vehicles are designed and assembled nearly completely under a single corporate structure.

[58] The U.S. Department of Energy announced in 2009 the selection of Navistar Corporation for a cost-shared award of up to US$10 million to develop, test, and deploy plug-in hybrid electric vehicle (PHEV) school buses.

Alongside the MaxxPro MRAP and the MXT-MV, Navistar Defense has developed military variants of the 5000 and 7000 severe-service trucks (today, the HX and HV-Series on-road).

[72] In early 2017, Navistar's truck assembly plant in Springfield, Ohio, began production of cutaway van chassis variants of the GMT610 Chevrolet Express and GMC Savana.

[73] Further details around the Chevy Silverado 4500HD/5500HD/6500HD were announced by General Motors early in 2018,[74] with Navistar also unveiling the International-branded variant of the truck, the CV series, shortly thereafter.

[75] The truck serves as a successor to the previously discontinued Chevrolet Kodiak and International TerraStar, competing against the Ford Super Duty F-450/F-550/F-600 and Ram Chassis Cab.

For the 1983 model year, Ford entered into a supply agreement with International Harvester to use the newly introduced IDI diesel V8 for 3⁄4 and 1-ton F-Series pickups and E-Series vans.

To create the low-cab COE, the frame (sourced from the Ford F-450/F-550 Super Duty) was mated with the cab of the Mazda Titan (converted to left-hand drive).

[80] On 16 September 2010, Anhui Jianghuai Automobile Co., Ltd. (JAC) announced joint ventures with NC2 Global and Navistar International Corporation that will develop, build, and market heavy duty trucks and diesel engines in China.

In 2001, to avoid bankruptcy, a group of administrative staff of Grupo Empresarial G, owners of the company remnants, carried out the financial restructuring of DINA Camiones.

In April, Navistar fired Deloitte, its independent auditor for 98 years, and hired KPMG to help restate earnings back to 2002 to fix accounting errors.

[89] In 2001, then CEO Dan Ustian faced numerous United States Environmental Protection Agency (EPA) regulations to reduce the amount of nitrogen oxides and soot emanating from diesel engines.

[94] In the meantime, Navistar's EGR decision had led to significant reliability issues and quality problems (which were ultimately traceable to the fundamental physical reality that recirculation of exhaust gas introduces intrinsically abrasive soot and inherently corrosive acid gases back into the engine).

[96] In December 2014, the United States Judicial Panel on Multidistrict Litigation ordered that 13 of 14 civil lawsuits brought against Navistar for MaxxForce engines would be consolidated into one case.

The consolidated lawsuits say Navistar's use of Advanced Exhaust Gas Recirculation emission control system, or EGR, was defective and resulted in repeated engine failures and frequent repairs and downtime.