The Swede got his first chance to sample Sprint Cup machinery driving the #83 Red Bull Toyota Camry, sharing the track with some of the series regulars as team regular Scott Speed was on hand, as well as JTG Daugherty's Marcos Ambrose and Earnhardt Ganassi's Juan Pablo Montoya.
Ekstrom was initially surprised at how the car drove but through the day he was able to familiarise himself with how its handling characteristics differed to his more nimble DTM Audi A4. While a Sprint Cup car has close to twice the power of a DTM machine, it also weighs nearly 500kg more and has less downforce.
In the end he came out satisfied with his first NASCAR experience.
"I was really surprised how the car drove," said Ekstrom. "Everyone had told me that it would be very special and it was quite nice. The first hour of the test I was fighting the car a lot just getting used to the power, the weight, and the fact that the car has little aero, all things that are very different for me.
"A few hours into the test I felt a lot more comfortable in the car and overall I think we had a really good test.
"I came into this test not having any experience in these type of cars, and also having never worked with the #83 team before, so it was nice to see how well we all worked together.
"I really enjoyed my first Sprint Cup test and am glad to have had this opportunity."
The 31-year-old was expected to contribute to the team's preparations for the first road course event of the season, which takes place at Infineon Raceway in Sonoma, California next month.
Red Bull has Casey Mears currently set as Brian Vickers' replacement, with the latter sidelined for the rest of the year due to blood clots.
According to Red Bull's Jay Frye, it is still to be determined whether Mears will actually drive the car in all remaining races of the season.
Ekstrom to test for Red Bull teamTaylor talk bemuses Magpies
