(Bloomberg) -- Volkswagen AG waited two months afteracknowledging a software abnormality in its cars to tell regulatorsthe algorithm was designed to cheat emissions tests, according to astaff memo prepared for lawmakers investigating the automaker.

The Energy and Commerce Committee, which will hold a hearing onThursday in Washington, also wants further details on how and whythe German-based automaker cheated on U.S. and California emissionstests, according to the memo. Committee staff met Monday withrepresentatives of VW and regulators in preparation forthe hearing.

The House hearing will add to the emerging record on what wenton behind the scenes at VW. By the time the panelconvenes, VW will have informed European regulators aboutsteps it intends to take to fix nearly 11 million vehicles.

VW’s initial disclosure to the California Air Resources Boardthat it had a “second calibration” governing engines duringemissions tests on three different diesel engines occurred on July8, according to the committee. It wasn’t until Sept. 3 that thecompany came clean with the Environmental Protection Agency andCARB that this alternative mode was a “defeat device,” shuttingdown pollution-control equipment as the cars drove in the realworld.

The Senate Finance Committee on Tuesday disclosed its owninvestigation into whether Volkswagen lied to the U.S. governmentin certifying its diesel vehicles as eligible for alternative motorvehicle tax credits, which are used to develop the market forhigher-cost, less polluting cars.

Volkswagen’s 2009 Jetta TDI Sedan and SportWagen modelsqualified for $1,300 per vehicle tax credits, and several 2010models were later certified as eligible, Senators Orrin Hatch, aUtah Republican, and Ron Wyden, an Oregon Democrat, said in aletter to VW executives on Tuesday. More than $50 millionin subsidies went to the cars’ buyers, they said.

VW’s remedy

The House panel is likely to ask VW executives andofficials from the EPA about fixes for cars and what consumers canexpect going forward, according to the memo.

“We really need more information about what motivated Volkswagento distrust their own engineering and their technology,” said DanBecker, director of the Safe Climate Campaign, a Washingtonenvironmentalist who has been following the scandal closely.

The software allowed the cars to pass pollution tests eventhough they emitted as much as 40 times the permitted amount ofsmog-forming nitrogen oxides, according to theEPA. VW has suspended sales of those vehicles and itschief executive officer, Martin Winterkorn, quit asinvestigators from Washington to Berlin have promised to punishthose responsible.

In a statement Tuesday, Volkswagen’s current Chief ExecutiveOfficer, Matthias Mueller, promised employees “swift and relentlessclarification” of what went wrong. Fixes for customers are“imminent,” he said.

“We can and we will overcome this crisis, because Volkswagen isa group with a strong foundation,” Mueller said. “Only wheneverything has been put on the table, when no single stone has beenleft unturned, only then will people begin to trust us again.”

Volkswagen’s top U.S. executive, Michael Horn, will testifyThursday. The panel will also hear from Christopher Grundler,director of EPA’s Office of Transportation and Air Quality, andPhillip Brooks, the agency’s director of air enforcement.

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