With gasoline prices high and rising, a new financial milestone has arrived: the $100 tank of gas.

Bryan Carisone, a heating and air-conditioning contractor in Raritan, N.J., “absolutely loves” his new GMC Denali XL, an extra-large sport utility vehicle with televisions built into the leather seats. But in June, one week after he bought it, he pulled into a station on a near-empty tank and watched the total climb higher and higher  to $109.

“It just about killed me,” Mr. Carisone said.

For decades, the $100 barrel stood as a hypothetical outlier in doom-and-gloom conversations about future oil prices. And nobody could even imagine an American family paying $100 to fill the tank.

But the future is here. Oil passed $100 a barrel in January and now seems headed toward $150 a barrel. Gasoline prices surpassed $4 a gallon on June 8, stalled for a while, and have been rising again in recent days, setting a record Saturday.

By late spring, owners of pickups and sport utility vehicles with 30-gallon tanks, like the Cadillac Escalade ESV and Chevrolet Suburban, started paying $100 or more to fill a near-empty tank. As gas prices continue to rise  the national average stood at about $4.10 a gallon Saturday  membership in the triple-digit club is growing. Now, even not-so-gargantuan Toyota Land Cruisers and GMC Yukons can cost $100 to fill up.