DETROIT, Feb 17 (Reuters) - Penske Corp. on Tuesday said it was buying an additional 357,123 shares of car dealership group UnitedAuto Group Inc. .
Penske, a diversified transportation services company, announced the transaction after UnitedAuto posted stronger fourth-quarter earnings, driven by higher sales of new and used vehicles.
Penske said the additional shares would raise its stake in UnitedAuto to 19.4 million shares, or 45.9 percent.