About eight months after he first threw out an idea that seemed “impossible,” Nipomo firefighter John Byrne has completed his goal.

On Christmas Day, Byrne surprised his younger sister with a modified Honda Element, purchased with money he raised bicycling 3,401 miles across the United States last fall.

Hundreds of people who learned about his cross-country trek donated about $62,000.

The money was more than enough to buy the car and have it converted by a San Luis Obispo company for 22-year-old Lauren Byrne, a quadriplegic who broke her neck in a swimming accident when she was 15. She’s now in a wheelchair and has limited use of her arms.

“This vehicle is going to give her so much freedom,” John Byrne said this week. “She’s just so strong, and I’m so happy that so many people donated to make this dream for her come true.”

Lauren Byrne, a Bay Area resident who is completing an associate degree at Ohlone College in Fremont, hopes to transfer to a four-year college and get a teaching credential. The car will help her maintain her independence, her brother said.

John Byrne, a fire apparatus engineer for Cal Fire in Nipomo, came up with an unusual idea in April as a way to raise money for a car: a bike ride across the country.

He started out in September from the Golden Gate Bridge, finishing at the Brooklyn Bridge 36 days later.

On Christmas Day, John Byrne told his sister they were going to have lunch at the fire station. Lauren Byrne had no idea of the surprise waiting for her, until they arrived at the station and the three bay doors opened, revealing two fire engines — and a black 2011 Honda Element with a big purple bow.

“It was a huge surprise,” Lauren Byrne recalled. “Everyone in the world knew before me. There were so many people there I couldn’t believe it.”

She started receiving driving lessons the following day, and hopes to take a driving test at a local DMV next week. Leftover money will go toward ongoing vehicle expenses, and some will be given to the San Luis Obispo County Firefighters Benevolent Association, which had accepted donations for John Byrne’s cause.

When asked what she thought about her brother’s undertaking, Lauren Byrne said she’s still absorbing it. “We’ll be in the car and I’ll be like, ‘I can’t believe you did that.’ It’s still unbelievable to me … but my brother is really something else.”

Reach Cynthia Lambert at 781-7929. Stay updated by following @SouthCountyBeat on Twitter.