Formula E is more of a competitor to the GP3 series than to Formula 1, according to Red Bull team boss Christian Horner.
Virgin founder Richard Branson said ahead of the Formula E finale in London that the all-electric series will surpass Formula 1 in popularity in the next "four or five years".
Horner, however, reckons the cars are too slow to be a direct competition to Formula 1, and he says the fact that drivers need to swap cars during the races is not sending a good message about its technology either.
"I watched the Formula E race on Sunday and it looks more of a competitor to GP3 than Formula 1," said Horner during a Red Bull media event on Tuesday.
"It's positioned totally differently to Formula 1, but it wasn't a focal point of racing.
"The cars look slow, the fact that you've got to change car half way through the race - I'm not sure it's delivering a great message about sustainable energy if you're saying your car can't get to the end of a grand prix or the end of a race without having to change cars.
"Of course, take nothing away from Formula E, I think they've done well to get where they are, but you can't compare it in the same sentences as Formula 1."
Horner does not believe Formula E technology will reach Formula 1 in the future.
"Not really, no. I don't think that's a direction we want to be heading down," he said.
The Red Bull boss did admit, however, that he enjoyed the idea of the FanBoost, used by the series to get fans to vote on which driver will get an additional energy boost during the race.
"That was the one thing I liked about it. The interaction with the fans was great, the fact that the fans can vote for their driver to get a FanBoost was something productive."