Exhibit 99.1

NAVISTAR REPORTS THIRD QUARTER RESULTS

LISLE, Ill. (September 6, 2012) — Navistar International Corporation (NYSE: NAV) today announced third quarter 2012 net income of $84 million, or $1.22 per diluted share, compared to third quarter 2011 net income of $1.4 billion, or $18.24 per diluted share. Current quarter results included an income tax benefit of $196 million that primarily resulted from a third quarter change in the company’s estimated annual effective tax rate, as well as the impact of $16 million in costs related to engineering integration and $10 million in non-conformance penalties (NCPs). The third quarter of 2011 included a $1.48 billion benefit from the release of a portion of the company’s income tax valuation allowance.

The company reported a pre-tax loss of $100 million in the third quarter 2012 versus a $54 million loss in the third quarter 2011. Revenues in the quarter were $3.3 billion, down 6 percent from the third quarter of 2011. The loss was driven by lower net sales in the company’s U.S. and Canada truck and engine segments, primarily due to lower military sales and reduced engine volumes in South America, respectively.

“Clearly we are not pleased with these results,” said Lewis B. Campbell, Navistar chairman and chief executive officer. “However, I was satisfied to learn on day one that Troy Clarke and his team were already working on a plan to deal with many of the important issues we face, most importantly restoring our core North American Truck, Engine and Parts businesses to their market leader positions. I believe we have good line of sight and a keen sense of urgency for moving forward.”

“Navistar is a great company with great people and great brands,” added Campbell. “With a laser focus on getting our quality right and hitting our clean engine launch dates, combined with actions to maximize cash flow and improve our balance sheet, I believe we can accelerate the pace of progress to deliver significant improvements during the next 12 to 18 months.”

The company announced that it is completing a voluntary separation program and a reduction in force of its salaried workforce. It anticipates these actions will generate $70 - $80 million in annual savings, which will contribute to Navistar’s overall goal to reduce costs by $150 - $175 million year-over-year, starting in fiscal year 2013. Additionally, Navistar is increasing efforts to cut discretionary spending and further reduce its material costs as part of its overall cost reduction program.

The company also announced it has launched a review of all of its non-core businesses with the goal of improving its return on invested capital and driving long-term profitability. As a result of this, along with uncertain industry conditions, the company is not providing fourth quarter earnings guidance until industry volumes solidify and these potential actions are defined.

EMISSIONS STRATEGY UPDATE

The company announced that it is on track to finalize its agreement with Cummins Inc. by the end of October 2012. As part of the agreement, Navistar will offer the Cummins ISX15 engine in certain truck models, expanding Navistar’s vehicle offerings. Navistar expects to launch the ISX15 in its ProStar+ model starting with initial customer deliveries in December 2012. Additionally, the agreement with Cummins Emission Solutions is on track to provide their proven selective catalytic reduction (SCR) aftertreatment system, which will be combined with Navistar’s MaxxForce 11- and 13-liter engines as part of the company’s clean engine solution. Navistar plans to begin production of its most popular 13-liter models with the SCR aftertreatment system in April 2013.

Last week, the U.S. Environmental Protection Agency (EPA) issued its Final Rule for NCPs for on-highway heavy-duty diesel engines, clearing the way for Navistar to continue to build and ship vehicles during the transition to its clean engine technology products.

“With the EPA Final Rule set to take effect and our progress with Cummins, we now have greater clarity on the transition to our new clean engine solution in 2013, which is our top priority,” said Troy Clarke, Navistar president and chief operating officer. “I am committed to ensuring that we remain diligent in achieving key milestones and delivering a smooth launch.”

SEGMENT REPORTING

Summary Financial Results:

Truck — For the third quarter 2012, the truck segment recorded a loss of $30 million, compared with a year-ago third quarter loss of $75 million. Segment results included charges of $11 million for engineering integration, compared to $129 million in engineering integration and restructuring charges in the third quarter of 2011.

The segment’s loss was driven by a combination of segment performance and deteriorating industry volumes, partially offset by manufacturing efficiencies. Year-over-year sales declined 5-percent, primarily due to lower military sales and decreased traditional volumes. Traditional chargeouts were down 7-percent, primarily due to a 22-percent decrease in Navistar’s Class 6 and 7 medium trucks, partially offset by a 32-percent increase in school bus volumes.

Engine — For the third quarter 2012, the engine segment recorded a loss of $47 million, compared with a year-ago third quarter profit of $32 million. The loss reflects lower sales volumes and $14 million in expenses related to non-conformance penalties and engineering integration.

Segment sales decreased by 13-percent, primarily due to lower sales volumes in South America, resulting from a pre-buy of pre-Euro V emissions engines in the prior year quarter. Partially offsetting the decrease in sales was lower SG&A and engineering spend.

Parts — For the third quarter 2012, the parts segment recorded profit of $73 million, compared with a year-ago third quarter profit of $70 million. The year-over-year increase was driven by continued improvements in commercial markets and lower SG&A expenses, partially offset by lower military sales.

Financial Services — For the third quarter 2012, the financial services segment recorded profit of $22 million, down from third quarter 2011 profit of $30 million primarily due to lower portfolio balances.

About Navistar

Navistar International Corporation (NYSE: NAV) is a holding company whose subsidiaries and affiliates produce International^® brand commercial and military trucks, MaxxForce^® brand diesel engines, IC Bus™ brand school and commercial buses and Navistar RV brands of recreational vehicles. It also is a private-label designer and manufacturer of diesel engines for the pickup truck, van and SUV markets. The company also provides truck and diesel engine service parts. Another affiliate offers financing services. Additional information is available at www.Navistar.com/newsroom.

Forward-Looking Statement

Information provided and statements contained in this report that are not purely historical are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995. Such forward-looking statements only speak as of the date of this report and the company assumes no obligation to update the information included in this report. Such forward-looking statements include information concerning our possible or assumed future results of operations, including descriptions of our business strategy. These statements often include words such as “believe,” “expect,” “anticipate,” “intend,” “plan,”

“estimate,” or similar expressions. These statements are not guarantees of performance or results and they involve risks, uncertainties, and assumptions. For a further description of these factors, see the risk factors set forth in our filings with the Securities and Exchange Commission, including our annual report on Form 10-K for the fiscal year ended October 31, 2011 and quarterly reports for fiscal 2012. Although we believe that these forward-looking statements are based on reasonable assumptions, there are many factors that could affect our actual financial results or results of operations and could cause actual results to differ materially from those in the forward-looking statements. All future written and oral forward-looking statements by us or persons acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to above. Except for our ongoing obligations to disclose material information as required by the federal securities laws, we do not have any obligations or intention to release publicly any revisions to any forward-looking statements to reflect events or circumstances in the future or to reflect the occurrence of unanticipated events.

Navistar International Corporation and Subsidiaries

Consolidated Statements of Operations

(Unaudited)

Navistar International Corporation and Subsidiaries

Consolidated Balance Sheets

Navistar International Corporation and Subsidiaries

Condensed Consolidated Statements of Cash Flows

(Unaudited)

Navistar International Corporation and Subsidiaries

Segment Reporting

(Unaudited)

We define segment profit (loss) as net income (loss) attributable to Navistar International Corporation excluding income tax benefit (expense). Our results from interim periods are not necessarily indicative of results for a full year. Selected financial information is as follows: