The Tesla Model 3 and BMW i4 are the most efficient EVs currently available in the UK, according to's new Efficiency Rating. Also known as the E-Rating, this tool lists real-world efficiency ratings for EVs to help buyers comprehend the overall efficiency of an electric car.

E-Rating uses an algorithm that considers several important factors. They include how well electrical power is converted into miles on the road, the speed at which the battery can be recharged, as well as energy-saving features such as heat pumps, intelligent brake energy recuperation, and climate control preconditioning. It also takes into account the team's experience of driving, testing and reviewing electric cars in the real world. 

The Tesla Model 3 Long Range and BMW i4 top the E-Rating list and are the only EVs to get A++ scores. At the other end of the spectrum, the Mercedes-Benz EQV is the least efficient with an E rating, while the Mercedes-Benz EQC and Audi e-tron share the second-to-last position with a D rating each.

There are 13 models with A+ ratings, including the Hyundai Ioniq, Citroën e-C4, and Fiat 500e, plus a further 14 with A ratings, including the Audi Q4 e-tron, BMW iX3, and DS 3 Crossback.

Gallery: 2021 Tesla Model 3

The cool thing about E-Rating’s smart algorithm is that it turns complex factors into a simple to understand score from A++ down to E, helping buyers choose the right car for them to save money and time at the charger. 

Looking at the miles per kWh rating (obtained by dividing the official WLTP range by battery capacity in kWh), calculated the cost difference to cover 10,000 miles between an A++ rated car (the BMW i4) and a car graded E (Mercedes EQV) to be £580.

With the number of EVs in the UK expected to top 300,000 in 2021, the website estimates that the difference in cost between charging the most and least efficient cars represents £155 million annually in electricity costs.

Besides the extra cost to charge the least efficient cars, owners will also find themselves waiting for a charge much longer—partly because less efficient EVs use more energy to move, but also because they can take charge at a slower rate. 

“It amazes me that until now we haven’t had an effective efficiency standard for electric cars, as we do across other sectors; but we’ve looked to put this right. As electricity costs less than petrol or diesel, it is easy to dismiss the efficiency of electric cars and think it isn’t important. But the costs of a less efficient model can soon add up. Perhaps more importantly, an electric car that is more frugal will go further and spend less time charging, meaning greater convenience for consumers.”

Ginny Buckley, founder of

The team and the Tesla Model 3's E-Rating

Here’s the full list of EVs the website has tested and their efficiency ratings, from the best to the worst: 

  • Tesla Model 3 : A++ 
  • BMW i4 : A++ 
  • Hyundai Ioniq : A+ 
  • Citroën e-C4 : A+ 
  • Fiat 500e : A+ 
  • Hyundai Kona Electric : A+ 
  • Mercedes EQS : A+ 
  • Kia EV6 : A+ 
  • Peugeot e208 : A+ 
  • SEAT Mii : A+ 
  • Tesla Model Y : A+ 
  •  Vauxhall Corsa-e : A+ 
  • Citroën Ami : A+ 
  • Volkswagen ID.3 : A+ 
  • Renault Twizy : A+ 
  • Hyundai IONIQ 5 A+ 
  • Audi Q4 e-tron : A 
  • BMW iX3 : A 
  • DS3 Crossback : A 
  • Ford Mustang Mach-E : A 
  • Kia e-Niro : A 
  • Kia Soul : A 
  • Peugeot e-2008 : A 
  • Renault Zoe : A 
  • Skoda Enyaq : A 
  • Smart EQ ForTwo : A 
  • Tesla Model S : A 
  • Tesla Model X : A 
  • Vauxhall Mokka : A 
  • Volkswagen ID.4 : A 
  • Audi e-tron GT : B 
  • BMW i3 : B 
  • BMW iX : B 
  • Mercedes EQA : B
  • MG MG5 EV : B 
  • MG ZS EV : B 
  • Nissan Leaf : B 
  • Polestar 2 : B 
  • Volvo XC40 Recharge : B 
  • Honda e : C 
  • Jaguar i-Pace : C 
  • Lexus UX300e : C 
  • Mazda MX-30 : C 
  • Porsche Taycan : C 
  • Rimac Nevera : C 
  • Citroën e-Spacetourer : C 
  • Vauxhall Vivaro-e : C 
  • Audi e-tron : D 
  • Mercedes EQC : D 
  • Mercedes EQV : E