Currently holidaying in Formentera with the London-based actor, yesterday the couple appeared to get into a spot of bother when their car broke down.
Mischa and Sebastian were spotted standing in the street as they waited for assistance.
Caught in a spot of bother: Mischa Barton and
her boyfriend were spotted when their car broke down as they holiday in
Formentera, Spain
She showed off her legs in a pair of short pink denim shorts which she teamed with a neon pink one-piece.
The actress completed her summer look with a pair of pale pink studded pumps and a nude side bag.
Beach ready: Mischa donned a khaki jacket with a neon pink one piece and a pair of shorts
Assessing the damage: Sebastian appeared to be trying to work out the problem
Not fazed: The 26-year-old touched up her makeup as she waited for some roadside assistance
Passing the time: The couple drank and ate as they tried to keep themselves occupied
As her boyfriend assessed the damage of the vehicle from a distance, the actress was seen touching up her make up.
The couple removed their belongings from the boot of the car when assistance arrived on scene and towed the car away.
Unloading the boot: Barton and London-based actor Knapp removed items from their car
Adventurous day: The brunette appeared to be explaining something as the vehicle got taken away
Getting closer: Mischa and Sebastian cuddled as the car got hooked up to the truck
Making the rest of the journey on foot? The couple's car was pictured as it was towed away
Where do we go from here: Mischa and Sebastian appeared to be planning their next move
In the grayscale photo, the brunette is sitting on a large rock in front of the sea in a one piece bathing suit.
Enjoying her time in Spain, on Tuesday, she tweeted: 'Love Formentera.'
'Love Formentera': Mischa uploaded a picture of herself sitting by the beach in a one piece bikini
Mischa appeared to be wearing no make-up, as she donned a pink lace dress that featured sheer billowing sleeves and a white star print.
She teamed the garment with white plimsolls and quirky sunglasses and even enjoyed a beer with her beau before making her way to the airport.
Different look: Mischa wore a pink and white lace dress as she prepared to leave Ibiza earlier this week
Have it your way: Sebastian was spotted holding a Burger King as his girlfriend adjusted her sunglasses
On to the next location: Mischa was seen loading her luggage into a waiting vehicle
'Perhaps
if I carry her far enough she'll sleep with me...': New research has
shown that most men would jump into bed with their female friends at the
drop of a hat
Rings
true: When Harry Met Sally, starring Billy Crystal and Meg Ryan, posed
the question of whether men and women can ever be just friends
Loyal
shoulder to cry on: But the male friends of many women secretly yearn
for their relationships to escalate beyond the purely platonic, research
shows
Keep
those feelings hidden: Any attempt by men to get their secret feelings
for female friends out into the open is liable to backfire, this writer
advises
Caggie
Dunlop strips off to her underwear in the music video for Lonsdale Boys
Club Ready To Go in order to attract lead singer Charlie Weaver

Saucy Caggie does her laundry dressed in just a pair of red underwear and a white bra as Charlie looks on
Caggie's cunning plans works as the pair start flirting in the laundrette while waiting for their clothes
Flirty! Charlie admires Caggie's figure as the pair frolic in the pool

The loved up pair finally go to catch up with their friends after spending time flirting and canoodling in the pool
Can't get enough: Imogen Thomas is gripped by the erotically charged bestseller 50 Shades of Grey
Thomas tweeted: 'Loving and addicted to 50 shades of grey: dominant or submissive which one are you?'
Summer loving: Thomas is clearly enjoying the London weather at the moment
Relaxed: The Welsh beauty is all smiles after sunning it up in the pool
Ice cool: Thomas was out in the London sun yesterday, where was caught suggestively sucking an ice lolly
There for her: Jedward accompanied their pal Tara Reid on a stroll along the beach in St Tropez yesterday
Cosy: Tara seemed more than comfortable in the twins' company, linking arms and holding hands with them
Smartened up: John and Edward had taken the time to restore their hair to its usual vertical style
'I can handle this!': Either John or Edward seemed fairly determined to take a canoe for a spin
Having trouble walking in those? Jedward's trousers were if possible even tighter than ever
Helping her recover: The relentlessly positive twins must be perfect company for Tara, who has recently been in hospital
Entertaining themselves: The threesome hit Club 55 together
Just what she needed: Tara has tweeted that she is feeling much better
Party time: Tara Reid and Jedward enjoyed the sunshine in Saint Tropez, France, yesterday afternoon
Real heroes: Jedward wore Superman vests and tiger stripe trousers with red trainers
Walk this way: Tara looked back at her best as she and Jedward headed for lunch at Club 55
Novelist Marion McGilvary has opened up about how lonely an empty house can feel
Marion McGilvary says too much 'me time' leaves her feeling lonely
Bright spark: Minnie Driver was a sight for sore eyes in a pair of electric pink workout leggings today

Eye-catching style: Minnie also sported a simple white top and trainers and off-set the neon with a cobalt blue handbag
Fantastic at 42: It's no wonder Minnie is happy to show off her figure when she looks so good in skin-tight leggings
On the go: Minnie made a phone call as she hurried through Beverly Hills to get to her exercise session
Fuss-free: The star appeared to be wearing no make-up but covered up her face with a pair of aviator sunglasses
Family time: Minnie enjoyed a day out with her three-year-old son Henry in Malibu over the weekend