Don't take those gasoline prices under $4 a gallon – and in many areas, under $3.50 – for granted.

Petroleum analyst Gregg Laskoski of GasBuddy.com tells the Los Angeles Times, "Even with increasing energy production in the U.S., declining fuel consumption, and improving fuel efficiency, Americans may still face rising gasoline prices in 2013."

Several factors could cause fuel prices to start heading up again:

• The value of the U.S. dollar (if it drops, crude oil will cost more)
• Whether U.S. oil exports continue to climb
• Possible hurricanes or other weather emergencies
• The ability of refineries to remain in operation (when several on the West Coast closed for repairs last fall, prices out West jumped).

Right now, average U.S. prices are just under $3.30 a gallon. But they're expected to hit $3.95 by April, then fall back to $3.60 to $3.73 this summer. But big city drivers will pay a lot more with prices in Los Angeles, Chicago and New York flirting with the mid-$4's.