IndyCar? Sports cars? Formula E.

The list continues to grow of testing opportunities being floated at four-time Formula 1 champion Sebastian Vettel. Funny thing is, Vettel is not acting like a driver who's looking to leave Formula 1 anytime soon.

The 34-year-old German, who is undecided about signing another contract with Aston Martin beyond 2022, has already been invited to test an IndyCar. He has another offer to work alongside F1 legend Gerhard Berger in the German DTM series, racing sports cars.

Now, Thomas Chevaucher, team principal of the DS Techeetah Formula E team, is inviting Vettel to Formula E.

The French team has won the all-electric series twice, and runs former Red Bull F1 driver Jean-Eric Vergne.

"Sebastian is very interested in environmental protection and has climate change in mind, just like we do in Formula E," Chevaucher told European media outlet Auto Bild. "We do not know to what extent he is interested in continuing his career in Formula E, but we would like to give him the opportunity to try out a CO2-neutral racing car."