The 49-year-old handbag designer was spotted at the pump in a casual outfit for the solo outing.
Her sighting came just weeks after her ex-husband Kevin Costner was seen partying with celebs like Jewel, Emma Stone and Michael Bolton at Richard Branson’s private island over the Thanksgiving holiday.
Baumgartner stepped out in a stylish grey sweater with her blonde locks pulled back into a messy bun.
She had black sunglasses tucked into the collar of her sweater, while opting for tan pants for the casual outing.
She completed her look with matching brown shoes with white soles for her Montecito outing on Monday.
Baumgartner and Costner starting dating in 2000, with the actor and designer tying the knot at his Aspen, Colorado in 2004.
They share three kids – Cayden Wyatt, 16, Hayes Logan, 14, and Grace Avery, 13 – with Costner also sharing four more kids with three women from previous relationships.
He shares Annie, 39, Lily, 37, and Joe, 35, with first wife Cindy Silva, who were married from 1978 to 1994, with Silva filing for divorce after her ex allegedly had an affair on the set of the movie Waterworld.
He also shares 26-year-old son Liam with Bridget Rooney, the niece of Pittsburgh Steelers owner Dan Rooney.
Fans were taken by surprise when Baumgartner filed for divorce in May, with rumors swirling that both Costner and Baumgartner were unfaithful.
A source claimed, ‘Kevin was very surprised by Christine’s actions, he obviously doesn’t want the divorce and he would take her back.’
‘It’s disappointing, he loves her and he loves his children,’ the statement concluded, with a rep adding cheating allegations are, ‘absoluely untrue.’
The divorce was finalized in September, with Costner ordered to pay $63,209 a month in child support payments.
Costner was tentatively ordered to pay $129,755 a month in an initial hearing, though Baumgartner then asked for $175,057 a month during a Santa Barbara hearing in August.
Baumgartner’s attorney John Rydell claimed the increase was so Baumgartner could maintain their oceanside lifestyle, which was, ‘in their DNA at this point.’
‘Kevin and Christine Costner have come to an amicable and mutually agreed upon resolution of all issues pertaining to their divorce proceedings,’ a statement read.