Exhibit 99.1

FOR RELEASE: IMMEDIATE

GATX CORPORATION REPORTS 2012 FIRST QUARTER RESULTS

CHICAGO, IL, April 26, 2012 – GATX Corporation (NYSE:GMT) today reported 2012 first quarter net income of $30.3 million or $.64 per diluted share, compared to net income of $19.9 million or $.42 per diluted share in the first quarter of 2011. The 2012 and 2011 first quarter results include the aggregate impact from Tax Benefits and Other Items of negative $2.2 million or $.05 per diluted share and positive $6.4 million or $.14 per diluted share, respectively. Details related to the Tax Benefits and Other Items are provided in the attached Supplemental Information.

Brian A. Kenney, president and chief executive officer of GATX, said, “Demand for most railcar types in our fleet continues to be strong. GATX’s North American fleet utilization improved to 98.5% at the end of the first quarter. The commercial team remains focused on improving lease rates while also increasing lease terms on many car types. GATX’s Lease Price Index (“LPI”) was a positive 19.2% with an average renewal term of 55 months, and the renewal success rate was over 80%.

Mr. Kenney added, “We continue to take delivery of new railcars under our five-year supply agreement, and we are placing these cars on long-term leases at very attractive rates. We are also taking delivery of new tank cars in Europe and achieving favorable lease terms.

“American Steamship Company’s (“ASC”) sailing season began in late March. Based on early indications from our customers, ASC expects to move modestly more tonnage in 2012 than in 2011. Results in the Portfolio Management segment were solid as we executed on planned asset remarketing activity during the quarter.”

Mr. Kenney concluded, “Our 2012 full-year earnings estimate remains unchanged at $2.40—$2.60 per diluted share, excluding the impact of Tax Benefits and Other Items.”

RAIL

Rail segment profit was $58.6 million in the first quarter of 2012, compared to $51.6 million in the first quarter of 2011. The 2012 and 2011 first quarter results include the pre-tax impact from Other Items of negative $2.5 million and positive $7.2 million, respectively. The improvement in segment profit was driven by increasing lease rates and lower maintenance expense due to the high renewal success rate in North America.

At March 31, 2012, Rail’s wholly-owned North American fleet totaled approximately 109,000 cars, and fleet utilization was 98.5% compared to 98.2% at year end and 97.8% at March 31, 2011. The European wholly-owned tank car fleet totaled approximately 21,000 cars and utilization was 96.7% compared to 97.1% at year end and 95.8% at March 31, 2011.

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During the first quarter of 2012, the change in the Lease Price Index (“LPI”) was a positive 19.2%. This compares to a positive 13.2% in the prior quarter and a negative 0.5% in the first quarter 2011. The average lease renewal term for cars in the LPI during the first quarter was 55 months compared to 48 months in the 2011 fourth quarter and 41 months in the prior year period. Rail’s investment volume, driven by new railcar purchases in North America and Europe, was $143.7 million.

Additional current and historical fleet and operating data as well as macroeconomic data related to Rail’s business can be found on the last page of this press release.

AMERICAN STEAMSHIP COMPANY

American Steamship Company (“ASC”) reported segment profit of $2.1 million in the first quarter 2012 compared to $0.8 million in the first quarter 2011. ASC’s operations are limited during the first quarter as the vessels are in winter lay up from mid-January through late March.

PORTFOLIO MANAGEMENT

Portfolio Management reported segment profit of $22.0 million in the first quarter of 2012 compared to $10.7 million in the prior year period. The increase in segment profit was due to an increase in asset remarketing activity.

The Portfolio Management segment currently consists of approximately $831.4 million of owned assets (including on and off balance sheet assets) and third-party managed portfolios totaling approximately $154.1 million.

COMPANY DESCRIPTION

GATX Corporation (NYSE:GMT) strives to be recognized as the finest railcar leasing company in the world by its customers, its shareholders, its employees and the communities where it operates. Controlling one of the largest railcar fleets in the world, GATX has been providing quality railcars and services to its customers for 114 years. GATX has been headquartered in Chicago, Illinois since its founding in 1898 and has traded on the New York Stock Exchange since 1916. For more information, visit the Company’s website at www.gatx.com.

TELECONFERENCE INFORMATION

GATX Corporation will host a teleconference to discuss 2012 first quarter. Teleconference details are as follows:

Thursday, April 26^th

11:00 A.M. Eastern Time

Domestic Dial-In: 1-800-895-0231

International Dial-In: 1-785-424-1054

Replay: 1-888-203-1112 or 1-719-457-0820 /Access Code: 4574425

Call-in details, a copy of this press release and real-time audio access are available at www.gatx.com. Please access the call 15 minutes prior to the start time. Following the call, a replay will be available on the same site.

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FORWARD-LOOKING STATEMENTS

This document contains statements that may constitute forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934 and are subject to the safe harbor provisions of those sections and the Private Securities Litigation Reform Act of 1995. Some of these statements may be identified by words like “anticipate,” “believe,” “estimate,” “expect,” “intend,” “plan,” “predict,” “project” or other similar words. Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties, including those described in GATX’s Annual Report on Form 10-K for the year ended December 31, 2011 and other filings with the SEC, and that actual results or developments may differ materially from those in the forward-looking statements.

Specific factors that might cause actual results to differ from expectations include, but are not limited to, (1) general economic, market, regulatory and political conditions affecting the rail, marine and other industries served by GATX and its customers; (2) competitive factors in GATX’s primary markets, including lease pricing and asset availability; (3) lease rates, utilization levels and operating costs in GATX’s primary operating segments; (4) conditions in the capital markets or changes in GATX’s credit ratings and financing costs; (5) risks related to compliance with, or changes to, laws, rules and regulations applicable to GATX and its rail, marine and other assets; (6) costs associated with maintenance initiatives; (7) operational and financial risks associated with long-term railcar purchase commitments; (8) changes in loss provision levels within GATX’s portfolio; (9) conditions affecting certain assets, customers or regions where GATX has a large investment; (10) impaired asset charges that may result from changing market conditions or portfolio management decisions implemented by GATX; (11) opportunities for remarketing income; (12) labor relations with unions representing GATX employees; and (13) the outcome of pending or threatened litigation.

Given these risks and uncertainties, readers are cautioned not to place undue reliance on these forward-looking statements, which reflect management’s analysis, judgment, belief or expectation only as of the date hereof. GATX has based these forward-looking statements on information currently available and disclaims any intention or obligation to update or revise these forward-looking statements to reflect subsequent events or circumstances.

FOR FURTHER INFORMATION CONTACT:

GATX Corporation

Jennifer Van Aken

312-621-6689

jennifer.vanaken@gatx.com

Investor, corporate, financial, historical financial, photographic and news release information may be found at www.gatx.com.

(4/26/12)

—Tabular Follows—

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GATX CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(In Millions, Except Per Share Data)

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GATX CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(In Millions, Except Per Share Data)

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GATX CORPORATION AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS (UNAUDITED)

(In Millions)

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GATX CORPORATION AND SUBSIDIARIES

SEGMENT DATA (UNAUDITED)

Three Months Ended March 31, 2012

(In Millions)

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GATX CORPORATION AND SUBSIDIARIES

SEGMENT DATA (UNAUDITED)

Three Months Ended March 31, 2011

(In Millions)

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GATX CORPORATION AND SUBSIDIARIES

SUPPLEMENTAL INFORMATION (UNAUDITED)

(In Millions, Except Per Share Data)

Tax Benefits and Other Items impact on Net Income:

Tax Benefits and Other Items impact on Diluted Earnings Per Share:

Management believes that highlighting these items allows the reader to better analyze ongoing operating results and trends.

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GATX CORPORATION AND SUBSIDIARIES

SUPPLEMENTAL INFORMATION (UNAUDITED)

(In Millions, Except Leverage)

(Continued)

+ Capital Lease Obligations + Commercial Paper and Bank Credit Facilities, Net of Unrestricted Cash

Reconciliation of Total Assets to Total Assets (including off-balance sheet assets), Excluding Cash:

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GATX CORPORATION AND SUBSIDIARIES

SUPPLEMENTAL INFORMATION (UNAUDITED)

(Continued)