Tesla Motors' charging stations for electric cars can be described as the fastest currently available in the world, the UK's ad watchdog has ruled.

While there might be EV charging technology which might one day surpass Tesla's stations, specifically the Chinese GB/T charging standard, the American company was found to be unsurpassed in the current market.

The Advertising Standards Authority investigated two complaints from British green energy company Ecotricity—which operates a number of EV charging stations in the UK—about claims Tesla had made on its website in October last year.

The manufacturer had said that its proprietary Supercharger is “The World’s Fastest Charging Station,” and that a Tesla Model S bought for £48,500 could offer owners "£6,500 estimated petrol & tax savings over 5 years."

Tesla successfully argued that there are just four types of EV charging station in the world which use the faster direct current (DC): its own Supercharger, CHAdeMo, the SAE Combo station, and the Chinese GB/T (guó biāo/tuījiàn) EV charging standard. Other stations charge using alternating current (AC), but they are demonstrably slower.

The ASA upheld Tesla's claims that the 120kW of power that Superchargers deliver to their cars' batteries beat the other varieties. CHAdeMO managed 50kW, SAE Combo 60kW, and GB/T 50kW. The firm conceded that theoretically speaking, GB/T could max out at a whopping 180kW, but that the technology had not achieved real-world application available to consumers. The regulator said:

We noted that the GB/T charger, developed for use with GuoBiao cars, was theoretically capable of delivering more power than the Tesla Supercharger. However, because we considered consumers would understand the claim to relate to actual charging speeds of currently available EVs, we considered the theoretical power delivery capabilities of the chargers were not relevant. We noted that the Tesla Model S could accept 120 kW of power, whereas the maximum that other EVs could accept was 60 kW. We therefore understood that the Tesla Supercharger was faster at charging compatible EVs than any charger used worldwide. On that basis, we concluded the claim had been substantiated and was not misleading.

The ASA also accepted that the calculations Tesla had made for the savings its Model S owners would make—£6,500 over five years—were based on realistic estimates of petrol and electricity price fluctuations, and that the claim was not misleading to the public.

This isn't the first time that Tesla and Ecotricity have crossed swords over ad claims. In April, Tesla failed to convince the ASA that Ecotricity was misleading folk with its claim to offer the "greenest electricity," and "the greenest energy" to Brits.