Before Tesla Inc. CEO Elon Musk returned to the U.S. after a three-day visit to Germany, he made a final stopover to meet with one of his biggest competitors — Volkswagen Group CEO Herbert Diess.

The two auto executives met for about two hours on Thursday evening at a small airport in Brunswick, where Musk test-drove VW’s ID3 electric compact car, according to people familiar with the matter. Musk also inspected the ID4 electric SUV that VW will launch later this year, said the people, who asked not to be identified as the meeting wasn’t public.

A VW Group spokesman confirmed that Diess met with Musk, but declined to comment on details.

Musk had toured Europe’s largest economy since Tuesday, visiting pharmaceutical company Curevac, before moving on to Berlin for meetings with politicians and a visit of the factory Tesla is building outside the German capital in Gruenheide.

The site would be Tesla’s first assembly plant in Europe and could produce as many as 500,000 vehicles a year, underpinning Musk’s attack on the German auto establishment.

Diess has praised Musk’s achievements several times in the past, both publicly and during internal events.

The VW Group CEO on Friday lauded his rival yet again, saying in a LinkedIn post that Tesla’s new factory brings “trend-setting future automotive technology” to Germany.

“Tesla will liven up the competition in Germany and accelerates the transformation of our established industry significantly,” he said.