Four-time Formula 1 champion Sebastian Vettel has slapped down the rise of the all-electric Formula E series, claiming it is not highly regarded by those in motorsport.

The championship recent began its fourth season, with Sam Bird and Felix Rosenqvist winning a double-header this past weekend in Hong Kong. In that time it has become perhaps the most attractive place for manufacturer entries with the likes of Audi, Renault, Jaguar, Citroen and more all involved with Mercedes and Porsche joining in 2019.

Yet in its current form, with two cars needed to complete a race and a level of performance comparable to a Formula 3 car, the series doesn't impress Vettel.

"To me, this is not the future," the German told Swiss newspaper Blick. "E-mobility is currently very popular in the world but anyone who is honest and identifies with motor racing does not think much of Formula E."

The grid is largely comprised of WEC and former F1 drivers have taken to Formula E to compete with the first three champions, Nelson Piquet Jr., Sebastien Buemi and Lucas di Grassi, all once members of the F1 grid.

And though publicly they claim the driving style needed and the risk of racing on street circuits make for a good challenge, Vettel claimed: "The cars are not very fast and many drivers who drive there tell me that the driving is not very exciting."

Given the current battle going on over the future of F1, it will be interesting to see how the future of Formula E develops with Nico Rosberg linked to the Mercedes project and Felipe Massa admitting his interest after previously testing with Jaguar.