Volkswagen Group said Tuesday that its internal emissions testing has found “irregularities” in about 800,000 cars worldwide, adding an estimated $2.2 billion to the automaker’s tab to make amends for the growing scandal.

The problem does not involve VW vehicles in the U.S., Volkswagen of America spokesman Mario Guerreiro said.

The new admission underscores that VW’s problems are global, even though its emissions issues surfaced in the U.S. in September with regulators accusing the automaker of rigging nearly 500,000 vehicles to avoid emissions requirements.

Volkswagen said in a statement from Germany that the issue this time is carbon dioxide. Most of the engines involved are diesels, but  Guerreiro says some involve a 1.4-liter gas engine with a cylinder-deactivation feature aimed at saving more fuel. It marks the first time that emissions troubles have been mentioned in regard to gas, not just diesel, powerplants.

The automaker also said it set some gas-mileage estimates too high, which opens yet another avenue for trouble. “It was established that the CO2 levels, and thus the fuel-consumption figures, for some models were set too low during the CO2 certification process,” said a Volkswagen spokesman in Germany, Christian Buhlmann.

In the U.S., Ford and Hyundai are among the automakers in recent years that have faced penalties and civil litigation for overstating fuel economy.

Volkswagen has already admitted to inserting software into 11 million diesel-powered vehicles worldwide that rigged their emissions systems to cheat testing. The admission came a day after the U.S. Environmental Protection Agency issued another citation against VW, alleging some models of VW, Porsche and Audi SUVs and luxury cars also appeared to cheat emissions laws.

Volkswagen denies that software was inserted in the latest batch of vehicles to beat the law.  Even though it is disputing the contention, VW Group’s Porsche division in the U.S. said Tuesday it will stop selling the diesel version of the Cayenne SUV.

Volkswagen’s board “will immediately start a dialog with the responsible type approval agencies regarding the consequences of these findings,” the company said in a statement regarding its internal testing results.  “This should lead to a reliable assessment of the legal, and the subsequent economic, consequences of this not yet fully explained issue.”