Reese, 32, won an Oscar for portraying country legend June Carter in 2005's Walk the Line. She was also on hand as a presenter at last week's Country Music Awards.

But the actress tells Fox News she likes to belt out Southern jams when she's on the road, too.

"I pretend that I'm a country music singer in my car, and I'm really good in my car, amazing," Reese noted. "It's just when I get out of my car, I'm not very good at all."

Witherspoon's latest film, Four Christmases, will be released November 26, the day before Thanksgiving. It'll go toe-to-toe at the box office with the Nicole Kidman-Hugh Jackman starrer Australia.

As for the height difference between her (5' 2") and her 38-year-old co-star Vince Vaughn (6' 5"), Reese said, "They had to build ramps that were about the same size as where I should be. It was a challenge, especially the kissing scenes... And he had to pick me up for half the dancing. He's actually holding me in the air so we can stay in the same frame."

That sounds a bit toned down compared what's been said about the pair's rumored dislike for each other while making the romantic comedy.