As far as I am aware of, there isn’t a fic with the exact same plot (i.e. friends to lovers) but here are some great road trip fics. I included 100 Days for our other followers. - HKVoyage

100 Days by borogroves

Kurt and Blaine have been best friends (and nothing more) since the age of six. Now 22-year-old college graduates, they take a roadtrip around the USA, visiting every state in 100 days. Fifty states. Two boys. One love story.

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The Klaine Road Trip 2015 by numerous authors

In a collective effort by Klaine authors across the globe, Kurt and Blaine are off on their first big trip as a married couple! From New England to New Zealand, and as many places as they can reach in between, the newlyweds are hitting the road (and the air) for the adventure of a lifetime.

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Midnight Confessions by @chazzam 

A Thelma and Louise Klaine AU with some serious liberties taken (and NO major character death).  Kurt convinces Blaine, his best friend, to take a break from his emotionally abusive husband and spend a weekend with him in the mountains of West Virginia.  But when they stop for some drinks along the way, things take a horrific turn.  

And then things start to get interesting.

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I'll Be Home For Christmas by kellyb321

Kurt leaves behind everything he loves - job, friends, apartment - in NYC to move home to Ohio and help Burt. Blaine is living a life people would kill for, but he's not happy. He wants a big change, and his first Christmas home in 10 years might be it. Little does Kurt know that the hitchhiker he picks up on his way home will change his life in every way. Alternate Meeting.

~~~~~The Dapper Highwayman by MotherGoddamn

Heading back from college for the summer, Kurt decides to pick up a hitchhiker. And gets a lot more than a travelling companion

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Operation Klaine by BreeZombiee

Kurt and Blaine get sucked in by the infamous duo to go on a road trip through Ohio. Wes and David are heartset on getting the two boys together by the end of the journey. Let the chaos begin.

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Road Trip by JonasGeek

Rachel's brother, Blaine, is in a band and this summer they are headed to California for a Band Slam competition. Which can only mean one thing, road trip! The band invites Rachel and Kurt along. Things seem to be going nowhere for Kurt in the way of love, but with new found friendships and awesome tunes, will it all be worth the wait?

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Best Laid Plans by trufflemores_Glee_fic

Some Other Us by thatgleekychick

Slave!AU. In a world where orphaned minors are forced into slavery, Kurt and Blaine have been best friends, and completely inseparable, since the age of 9. But one day when they’re both fifteen, their worlds are shattered—and now they may never see each other again. Warning: Minor character death

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You Belong to Me by MotherGoddamn

Everyone knows that bond-servants get what they get. When Blaine enters the picture, it’s harder to remember that. [Slave AU.]

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Worthless/Priceless by captain pihkal and @anxioussquirrel

Kurt buys a beaten and abused Blaine at a slave market and helps him get better. 

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Threadbare by @merikg

Slave!Blaine AU.  Blaine is a service-slave owned by a hotel.  He is available for rent as a courtesy to guests to entertain them during their stay.  His life is irrevocably changed one night when he is called to to serve by fashion designer Kurt Hummel.  Very Klaine. 

Note: Part 1 of the Threadbare series

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Hold My Heart by universalromance

GKM Fill: Blaine is a carrier who is sold by his parents when they are in need of money. He is gifted to Kurt by his buyer in order to gain favour with newly elected Congressman Hummel. He is expecting to be mistreated the way he was always told but soon discovers that there is still good in some people. MPREG.

Note: This is the first part of the Treasure My Heart series

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With No Moonlight by @wastenotimewrites

AU. In a world where legal slavery exists in all continents except Europe, Kurt Hummel moves back to Lima after years spent in France. The idea of owning a person disgusts him but soon he meets a boy that changes his mind. Kurt wants nothing more than to own him. slave!Blaine

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Happy Reading!