Jack in the Box (NYSE:JBX) is the latest company to pique my investment interest. I'll tell you why in a second.

This morning, the company reported fourth-quarter earnings of $21.7 million, or $0.58 per share, ahead of the $0.49-per-share forecast the company issued in September (see "Jack Stays in the Box"). Adjusted for a $0.03-per-share gain from an extra week in this year's quarter and a $0.04-per-share charge in last year's quarter, earnings climbed 12% to $0.55 per diluted share. Meanwhile, revenues grew 20% to $593.9 million.

But here's what made me think about Jack: the company's Qdoba Mexican Grills.

Now, up the street from Fool HQ in Virginia is a McDonald's (NYSE:MCD) Chipotle, a stylish quick-serve Mexican restaurant that I have come to crave. Unfortunately, we don't have Chipotle out here in St. Louis yet. What we do have are several new Qdoba restaurants, which are directly comparable to Chipotle -- many even prefer it.

According to Jack in the Box, Qdoba was neutral to earnings in fiscal 2004 but is expected to be accretive to earnings in fiscal 2005. The company added 28 new company and franchised Qdoba restaurants during the quarter, versus only 17 new Jack in the Box restaurants. In all, the company finished the fiscal year with 177 Qdoba restaurants in operation, up from 111 just a year ago.

Meanwhile, same-store sales at Qdoba increased in the "high-single-digit" range during the quarter.

The flagship Jack in the Box restaurants, of which there were 2,006 by the end of the quarter, didn't look so bad either. Same-store sales at those locations were up 4.1% as the company continues its brand reinvention by adding premium food items and upgrading its locations.

Back to the financials. Jack in the Box completed the $35 million share repurchase program it announced in September, buying back 1.08 million shares at an average price of $32.46 per share. The company also forecast first-quarter earnings of $0.69 per share and fiscal 2005 earnings of $2.43.

Qdoba is still a relatively small part of Jack in the Box's operations. That said, it changes the way I look at the company. And while the company certainly hasn't established itself as a premium restaurant operator just yet, I might consider picking up shares at a bigger discount to today's price at 14.5 times 2005 earnings.

Fool contributor Jeff Hwang owns none of the companies mentioned above.