Alonso will skip the first test in Jerez as Felipe Massa and Pedro de La Rosa take to the Spanish circuit next week.
"The first test is a general test in which one checks that all the components are put together properly", he said at the launch of the F138.
"Given the short amount of time available, we have decided that I will concentrate on the following tests: testing in Barcelona is more useful for measuring performance as well as being a circuit we race on."
"In the meantime, I will continue with my preparation and will follow the Jerez test, keeping in touch with Felipe and Pedro and analysing the data acquired by the engineers. To be 100% fit from now ‘til November will require combining training and testing. I can’t say if it’s a nice car or if it’s good enough to make the difference, because tenths are not visible to the eye, you need to see them from the cockpit. Now, all we can do is concentrate on testing."
Massa added that he is keen to return to the track after a strong second half of 2012.
"The first test is very useful to understand the direction in which we should go and where we need to do the most work," he said.
"Last year, I had a very positive second half to the season and I really want to get back on track and continue with the work that has seen me improve a lot over the past years. My aim is always the same, to give my all, right from the start of the season."