Oil prices have plunged 54 percent since late June, and David Rubenstein, co-CEO of the private equity titan Carlyle Group, sees no reason to wait any further before investing in the energy sector.

"The great fortunes are usually made when prices are low," he tells CNBC. "Prices are very low in energy, and a lot of people are scrambling, and that's where you make a lot of money."

U.S. crude oil traded at $50.30 a barrel Tuesday afternoon after hitting a 5 ½-year low of $43 in January.

Rubenstein is particularly interested in distressed debt calling it "the single greatest new energy [investment] opportunity" at the January World Economic Forum in Davos, Switzerland, according to CNBC.

U.S. oil production has exploded recently, reaching its highest level in at least 32 years.

"We have a lot of oil and gas that's relatively cheap compared to its replacement value. And as a result of that I think it will be one of the great areas to invest over the next five to 10 years," Rubenstein tells CNBC.

While he likes renewable energy, Rubenstein thinks oil and natural gas are the places to invest. "I think renewable energy is a great thing and we might get to Heaven quicker by investing in it, but it's not clear you'll make money in it."

On the gasoline front, consumers had plenty to cheer about a month ago, when regular gasoline prices averaged $2.07 a gallon nationally, not far above five-year lows.

Now they have a little less to cheer about, with the price at $2.44, up 18 percent over the past month. To be sure, that level still represents a 29 percent drop from $3.46 a year ago.

The price has rebounded as refineries have shut down for maintenance. "There's a huge mountain of crude oil sitting out there, . . . but it's not getting to the refineries," says Aaron Task of Yahoo Finance.

That would suggest gas prices might fall back down after the maintenance is completed, although the approach of the summer driving season could serve to boost prices.

As for the economy, analysts have been surprised that the reduction in gas prices hasn't done much to boost consumer spending, which slipped 0.2 percent in January.

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