Dollar Thrifty Automotive Group has seen earnings increase in the second quarter or financial 2011, prompting the car rental giant to increase its full-year expectations.

The company reported a profit of $42.5 million, or $1.36 a share, for the three months ended June 30th, up from $42.3 million, or $1.40 cents, a year earlier.

This excludes the impact of derivatives, impairment charges and other items, earnings rose to $1.35 from $1.26.

As a result, the company again raised its profit expectations before interest, taxes, depreciation, and amortisation to a range of $270 million to $290 million.

“While we were pleased with our continued rental day growth during the quarter, the rate per day environment was a headwind, negatively impacting top line revenue growth,” said Dollar Thrifty president Scott Thompson.

He added the fleet decisions in the industry following the crisis in Japan impacted fleet levels and pricing in the quarter.

The company has been cooperating with Hertz Global Holdings Inc. (HTZ) and Avis Budget Group Inc. (CAR), as both seek regulatory approval for rival deals to buy out Dollar Thrifty.

Hertz last week extended its takeover bid for Dollar Thrifty another month.