The double Formula 1 world champion has joined Gazoo Racing South Africa for a two-day event in a desert roughly 600 miles from Johannesburg, near the town of Bokhara.
Toyota has brought two Hilux's to the test, which is taking place over small dunes and hard gravel.
Giniel de Villiers, a Dakar Rally winner, is advising Alonso during the test as is de Villiers' regular co-driver, Dennis Murphy.
"Maybe he will not like it, or maybe it's going to take too much time off his calendar to see the level of difficulty of competing in the Dakar," said team manager Glyn Hall.
"Fernando's skills are exceptional, we have seen that for the last 17 years. He has evolved to be one of the best in the world.
"One of the things Fernando has proved in the F1 races I've been to is that he has the ability to listen and think when he's driving on the limit and that is a skill that is key in the cross-country rallies, because you listen to a co-driver.
"But the rally is complicated and he has to think about it."
As well competing in the 2018/19 World Endurance Championship, the Spaniard will race at the 2019 Indianapolis 500 in May with McLaren.
Take a look at our photos below of Alonso testing the Dakar car as he continues to explore options outside of F1.
Bahrain International Circuit - Winter testing