GRANITE FALLS — Thirteen high school students shattered records and took home first- and second-place trophies at an international competition to create the most fuel-efficient vehicles possible.

Two teams from Granite Falls High School, the ShopGirls and UrbanAutos, raced in the Shell Eco-Marathon Americas this weekend with cars they designed and built.

The race wasn’t about speed. It was about fuel efficiency: highest miles per gallon wins.

The Granite Falls teens were among 1,000 high school and college students who competed this year. There were 124 teams from seven countries.

“I like the challenge the Shell Eco-Marathon brings to kids, not only in high school but in college,” said sophomore Kelsey Green, the 16-year-old driver of the UrbanAutos car. “It’s on a global scale.”

Freshman Hannah Yadon, 14, was one of four students on ShopGirls, which seven years ago was the first all-girls team to compete in the Eco-Marathon. She’s learned a lot about teamwork, she said.

Both teams scrambled to solve unexpected problems before the races — blown bearings, a leaky fuel tank and an engine that refused to start. It didn’t stop them from speeding past fuel-efficiency records set in past years by Granite Falls students.

“During the week we tried to make our car turn on because it wasn’t running before we left,” Yadon said. “We just tried to figure out problems and fix them.”

They got to Detroit on Tuesday and the ShopGirls managed to start their car Thursday morning, in time for technical inspections. They raced Saturday and took first place in the prototype diesel category. Their sleek, three-wheeled green and pink car got 1,115 mpg and landed them a $2,000 prize. The team’s previous record was 682 mpg.

UrbanAutos took second place in the urban concept diesel category, which requires cars to meet standards for being street legal, Green said. For example, they must have four wheels, blinkers and lights. Prototype diesel competitors, including the ShopGirls, can break those rules to create more fuel-efficient vehicles.

The UrbanAutos team stayed up past midnight Saturday to repair their bearings and fuel tank. They raced Sunday and got 524 mpg. They missed out on first place by 1.1 mpg but broke their previous record of 288 mpg and took home a $1,000 prize.

The UrbanAutos’ car weighed in at 330 pounds and the ShopGirls’ car weighed 204 pounds. The vehicles have been updated and adapted from past years with the help of teachers and volunteers. The Eco Car program is a career and technical class offered at the high school.

The ShopGirls’ biggest project this year was building a carbon fiber chassis and putting in a new engine and wiring for their prototype car. They used the same body as last year but repainted it, Yadon said.

UrbanAutos put in a new engine, fuel tank and wiring but ran out of time to build a new body. They hope to do that next year, Green said.

The students plan to talk about what went right, what went wrong and what they could do better next time. They want to start working on designs for next year’s race right away.

Michael Werner teaches the Eco Car class. Many people think of shop classes and hands-on learning as a fallback plan for students who struggle academically, but that’s not the case, he said. A different style of learning doesn’t make a student more or less intelligent.

“Kids that go to this venue are equally as bright as the ones who are 4.0 and Ivy League bound,” Werner said. “They just have different ambitions.”

This year, the Eco Car teams dedicated their races to Vervia Gabriel, a longtime supporter of career and technical education and of the Eco Car program in particular. Gabriel died of cancer in May 2015.

“She was the one who really started this all,” Werner said.

Gabriel started the program in 2009 when she applied for a $10,000 grant for women in nontraditional roles. She helped the teams land sponsorships and worked with the school district to make sure the class could be offered each year.

“She just had this conviction that we could do this,” Werner said. “She, more than I, probably had to move some roadblocks out of the way because it’s not a traditional class to have these kids building a car and racing.”

Gabriel’s name was on both cars so the students could carry her memory with them during the races.

“We really lost someone who was living and breathing it, who made things happen,” Werner said. “She brought people together. This was in loving memory of our hero.”

Kari Bray: 425-339-3439; kbray@heraldnet.com