Tesla will soon face competition in the luxury all-electric car segment after Porsche and Audi unveiled new all-electric models at the Frankfurt Auto Show.

Audi unveiled the concept car for its "e-tron quattro" vehicle, a sporty SUV, with a range of more than 500 km.

Porsche showed the prototype of its first battery-powered sports car, titled "Mission E." Similar in appearance to its iconic 911, it has an 800-volt electric powertrain with 600 horsepower that can accelerate to 100 km per hour in 3.5 seconds.

"When we designed this car, we knew it had to be a real Porsche," chief executive Matthias Müller said in an interview on the eve of the Frankfurt Motor Show. "It had to feel like a 911."

Tesla's Model X goes on sale Sept. 29, with presale orders already open. (Tesla) Neither Porsche or Audi will have these models to market until 2018. Tesla's first luxury electric crossover, the Model X, starts delivery on Sept. 29, giving it a head start.

But with such high-profile names, with established reputations as luxury automakers, entering the all-electric market, they could pose competition for Tesla down the road.

Both Porsche and Audi are owned by Volkswagen, the world's biggest automaker, and the move to all-electric could boost the credibility of the concept and thus help Tesla.

"It will certainly sharpen the public focus on electric vehicles and raise overall awareness. Consumers are also set to gain from growing offerings of electric cars, especially in the performance segment," Commerzbank analyst Sascha Gommel told Reuters.

Tesla's Elon Musk put his electric-car patents into the public domain last year in the hope of boosting development of competing electric car technology.

One of the most closely watched design elements will be how far the cars can travel without having to be recharged.

Tesla is at work developing a network of charging stations across North America and Europe.

That could help open doors for Volkswagen as many consumers are waiting for suitable infrastructure to be developed.

It's not known how the new cars will be priced — Tesla's Model X starts around $77,000 US.