(CBS) — Prices at the pump keep on plunging.

Nationally prices have bottomed out to the lowest since 2009, and that portends even better things to come, CBS 2’s Brad Edwards reports.

Chicago cab driver Tony Liauppa is doing well these days.

“Under $4 (a gallon) is good, we ain’t gonna have a problem,” he says.

“A lot of it is just good old supply and demand. Demand is weak. We’re talking about El Niño. It’s 50 here in Chicago. The Northeast has not consumed as much heating oil as it usually does,” says analyst Patrick DeHaan of website GasBuddy.

Prices tumbled Monday to a national average of $1.995, the best since 2009. AAA Auto Club says drivers have saved $115 billion this year at the pump – that’s an average of $550 in savings per driver.

Like many, Liauppa has doubled  down, going from a gas guzzler to a hybrid.

“Ten dollars – I go all day on it,” he says.

DeHaan says it’s possible some stations in the suburbs could see gas prices of less than $1.50 per gallon. In the city of Chicago, where gasoline is more expensive, prices could finally dip below $2 per gallon.