SOMERSET, Pa. (AP) -- The head of the nation's largest automaker took perhaps the most important car ride of his life Wednesday, traveling 500 miles, mostly over highway through four states, to Washington, D.C., where he will ask Congress for a second time to save his slumping company.

Two weeks ago Rick Wagoner flew to Washington on a corporate jet. This time the chief executive of General Motors Corp. made the trip in one of his company's black hybrid Chevrolet Malibu, driving part of the way. He periodically made calls on his cell phone while in the passenger seat and wore sunglasses to protect from the glare of a sunny day.

Wagoner will be back in the spotlight Thursday and Friday, along with fellow CEOs Alan Mulally of Ford Motor Co. and Robert Nardelli of Chrysler LLC, when they appear before the Senate Banking Committee and the House Financial Services Committee to appeal for financial aid totaling up to $34 billion. Wagoner's plea will be the most desperate. GM submitted a plan to Congress on Tuesday that called for $18 billion in loans and warned that the 100-year old iconic American company won't have enough money to run its business without an immediate cash infusion of $4 billion.

All three CEOs made the trip to Washington in high-mileage hybrid vehicles -- the types of cars critics say the Detroit Three should have been making more of instead of becoming enamored of higher-profit, less fuel-efficient vehicles like SUVs and Hummers.

Wagoner's Malibu was accompanied on Wednesday's trip by two other vehicles -- a Buick Lucerne, which runs on fuel that is 85 percent ethanol, and a Chevy Cobalt XFE, the brand's highest-mileage vehicle. He is expected to arrive at the hearing Thursday morning in a test version of the Chevy Volt, the extended-range electric vehicle GM is bringing out in late 2010.

A reporter tailed the caravan from the Ohio-Pennsylvania border to Washington, D.C. Traffic was light most of the way through Pennsylvania. The posted speed limit varied between 55 and 65 miles per hour. The caravan routinely exceeded the speed limit by about 5 mph.

The group made two stops, one at about 1 p.m. at the South Somerset Travel Plaza in western Pennsylvania, where they had lunch at a Quiznos sandwich shop. About 2½ hours later, they stopped at a Pilot gas station to fuel their vehicles, and Wagoner went inside to get coffee.

Taking to the road like regular Americans was necessary after the CEOs' last visit for hearings in November turned into a public relations disaster. Lawmakers learned that all three had flown in separate corporate jets to ask for the bailout dollars, and critics lambasted the CEOs.

When asked if the bad experience two weeks ago was the motivation for driving, GM spokesman Edd Snyder, who traveled in the caravan along with Wagoner, two engineers and two security guards, said making cars "is what we do for a living and people should see them."

Ford's Mulally, in an interview from the road Tuesday, had acknowledged the symbolism of driving.

"We need to demonstrate that we heard their concerns and show we are willing to change," he said in an e-mail. "This is a small way of showing that."

Wagoner's group arrived in Washington, D.C., during rush hour in heavy traffic on the Capital Beltway. They took the George Washington Memorial Parkway into the city, and stopped for the night at the JW Marriott Hotel, just blocks from the White House.

Wagoner and his colleagues got out of their cars and told a photographer they were tired and were planning to retire for the night, just a little after 5 p.m. Some members of the party did eventually go to the hotel restaurant in the evening but Wagoner wasn't among them.

The cheapest room at the JW Marriott goes for $399 per night. A suite goes for just under $800. A guest in the restaurant can buy a glass of Kendall Jackson Sauvignon Blanc for $15 and eat a $15 club sandwich with turkey, bacon and lettuce for the same price. A crabcake sandwich is the most expensive on the menu at $21.

GM's Snyder said Wagoner plans to drive back to Michigan, though he didn't say when. Driving round-trip cost about $100 per car, including gas and tolls.

Ford announced Tuesday that it will sell its five corporate jets, and GM said it would close its corporate jet operations on Jan. 1 and try to sell the remainder of the lease time on its seven aircraft.

Ron Gettelfinger, head of the United Auto Workers, will once again join Wagoner, Nardelli and Mulally before Congress. He is traveling to the hearings in Washington on a commercial flight, just as he did two weeks ago. Gettlefinger has typically traveled to other union business on commercial flights but is often seen driving to events near Detroit with his wife.

AP Auto Writer Tom Krisher in Detroit contributed to this report.