There’s more to the decision to fly or drive somewhere than a simple calculation of gas costs versus airfare.

There’s the driving time, the drain of driving, car rental costs, car maintenance costs and baggage fees to consider.

But the money factor is a good place to start.

Consumer go-to guy Clark Howard says think of your drive time as being in a taxi with the meter ticking — at 50 cents per mile.

“The farther you’re going on your vacation, the more it pays for you to fly instead of drive,” Howard said last week on his Headline News cable network show.

If it’s just two people, however, driving is often the cheaper way to go, says Howard.

But, he warned, car rental rates are up. And money saved on a discount airline ticket can be canceled out with money spent on a pricey rental car.

“Your ticket could be extra cheap, but you’re car rental could be a fortune,” Howard said.

So find a good deal on a car rental before buying that non-refundable flight ticket, he recommends.