Filling a car's gas tank is weighing on more than just a teenager's wallet this summer.
Just ask Nikki Vanden Hull, a 16-year-old high school junior from Olathe, Kan.
She knows of teens who have curtailed driving to visit other friends -- unless covering the cost of a few gallons of gas could be worked out.
"Gas is causing friendships to be tested," Vanden Hull said.
With stiff prices at the pump, many teens are putting the brakes on their driving habits -- and learning firsthand about energy conservation, about supply and demand, and about making trade-offs in their spending to be able to afford their gas purchases.
There is a silver lining with this. Numerous reports show gasoline consumption has been declining for weeks as drivers work harder to conserve.
Highway fatalities are down, too. While there are no hard numbers on motor vehicle deaths among teens, overall driving fatalities are down 9 percent through May compared with the first five months of 2007, according to the latest data from the National Safety Council.
"When the economy is in the tank and fuel prices are high, you typically see a decline in miles driven and traffic deaths," said a statement from John Ulczycki, executive director of the safety council.
Vanden Hull said she is working harder to conserve. And even though she doesn't own a car, she's thinking more about what she wants to buy -- definitely something that's fuel efficient. Unfortunately, she said, "it seems that all the cars with good miles per gallon are increasing in price and are less available."
Once she buys a car, her parents have agreed to pay for the gas to and from school. "Anything else, I will have to pay for myself," Vanden Hull said.
Samantha Schwartz is somewhat insulated from the high cost of gas since she still has a learner's permit. Still, the 16-year-old from Lawrence, Kan., has been working as a hostess at a restaurant to save up money for when she gets her driver's license this winter.
"My parents are helping quite a bit with gas because they would rather have me save the money I earned for college," Schwartz said.
Schwartz has been carpooling with friends to school and to activities, and her mother plans to give the drivers gas cards to help pay for at least a few gallons.
Daniel LaGree, a high school senior from Leawood, Kan., said record gas prices influenced his choice of jobs this summer. "I decided to work for a country club that was close to my house instead of a country club that had a higher pay rate but was further away," LaGree said. "I figured I would make more money by not having to drive so far."
Tim Olson, a senior at the University of Missouri-Rolla, drives an old Jeep Grand Cherokee.
"It gets terrible gas mileage and has a huge gas tank," said Olson. "It really stings when it costs almost $100 to fill up."
Olson said he is riding his bike to school a lot more, and when he does need to drive, higher fuel prices are "definitely a concern that I keep in mind."
In addition to their driving habits, teens also need to keep a close eye on routine maintenance issues, such as underinflated tires, that can rub off miles to the gallon.
According to the Car Care Council's Web site, excessive fuel use could also indicate more serious problems, such as worn spark plugs, blocked air filters, faulty thermostats and poor wheel alignment.
The council recommended one other way to save on gasoline: Remind your young driver that after every fill-up, twist the gas cap until he hears it click or there is a tight seal. Nearly 17 percent of the vehicles on the road have a loose gas cap, causing 147 million gallons of gas per year to vaporize into the atmosphere.
As for my own family, I have two teenage drivers, including the youngest, who recently turned 16 and filled up with his own money for the first time.
He paid $4 a gallon -- a milestone that I'm certain will stick with him for a long time to come. (I paid about 50 cents a gallon on my first fill-up in the early 1970s.)
It didn't take my teen long to realize how much gas he could burn through while driving to and from school and to friends' houses. "I just filled it up, and I'm already down to half a tank," he lamented recently.
Wait until he sees the car insurance bill.