President Barack Obama and President Lula da Silva of Brazil talked about the touchy topic of ethanol tariffs when they met for the first time on Saturday.

Asked about their discussions during a joint press conference, President Obama praised Brazil for its leadership in biofuels but acknowledged that “the issue of Brazilian ethanol coming into the United States has been a source of tension between the two countries” that is “not going to change overnight.”

President Lula said since this is the first meeting he has had with Obama he didn’t expect “an immediate answer” with regard to the tariff on Brazilian ethanol, but he “can’t also understand while the world is concerned with climate change and with carbon emissions that bring greenhouse effect, … clean fuel also gets tariffs.”

Lula added that “when President Obama comes to visit Brazil I’m going to ask him to get inside a car that is run by a flex-fuel engine and he will feel very comfortable.”

Obama responded that he “actually had a flex-fuel vehicle. But one of the problems here in the United States is that we don’t have enough gas stations that have biofuels in them. So that’s one of the areas that we need to change our distribution networks here in the United States.”