A new system for testing EV range is being called for after an investigation found huge shortfalls when it’s colder.
What Car? magazine discovered a difference of up to 38% in low temperatures on a single charge versus official figures.
Editor Steve Huntingford warned that the testing regime manufacturers have to put their vehicles through is ‘completely unrepresentative of real-world conditions’.
The magazine said official analysis under the worldwide harmonised light vehicles test procedure (WLTP) takes place in labs with an ambient temperature of 23C, with each model undergoing an ‘unrealistically gentle acceleration’ to record what distance they can cover before a battery with 100% charge goes flat.
What Car? carried out its own range tests on 12 electric cars that had been left in the open overnight in temperatures of between 6C and 10C.
The test team followed a route of some 15 miles on a Bedfordshire site, including 2.6 miles of simulated stop-start urban driving, four miles at a steady 50mph and eight miles at a constant 70mph to replicate motorway driving.
The largest discrepancy was found with the Lexus UX 300e Takumi, pictured at top, which costs around £57,100 and has an official stated range of 273 miles but was found to only be able to cover 170 miles – a 38% reduction.
Next was its RZ 450e Takumi stablemate, which costs around £74,000 and is advertised as having a 251-mile range but covered just 159 miles, some 37% less.
The third biggest shortfall was for the Volkswagen ID 7 Pro Match without heat pump, which costs around £51,600 and could only travel for 254 miles in the What Car? test, which was some 34% below the stated distance of 383 miles.
Huntingford said: ‘Official testing of electric car ranges is completely unrepresentative of real-world conditions, potentially leaving drivers disappointed and with insufficient mileage.
‘It is clear that the results obtained using WLTP methods are unsuitable.
‘We need a new system that provides achievable summer and winter figures so that prospective EV buyers can be confident the car they’re looking at will suit their needs.
‘Providing a single, overly optimistic figure doesn’t help anyone.’
Mike Hawes, chief executive of the SMMT, said: ‘Car makers are investing billions in developing zero-emission vehicles, with improved battery performance, range and charging times, to make them a compelling choice for all drivers.
‘As What Car? rightly acknowledges, car manufacturers are required by law to test all vehicles of all technologies to the same, repeatable official standard – the WLTP test – and publish these results within any advertising to help car buyers make comparisons between vehicles.
‘What Car? also acknowledges that there will always be a difference between lab tests and real-world use due to variations in conditions, terrain, load and driving style.
‘Cold weather in particular will have an impact on range, but this has not deterred consumers in countries such as Norway and Iceland, which have the world’s highest rates of EV ownership.’
The What Car? winter range test results in full (ranked from biggest to smallest shortfall in real-world test range)
1. Make and model: Lexus UX 300e Takumi
Official range: 273 miles
Test range: 170 miles
Shortfall: 37.9%
2. Make and model: Lexus RZ 450e Takumi
Official range: 251 miles
Test range: 159 miles
Shortfall: 36.7%
3. Make and model: Volkwagen ID 7 Pro Match (without heat pump)
Official range: 383 miles
Test range: 254 miles
Shortfall: 33.6%
4. Make and model: Jeep Avenger Electric Summit
Official range: 244 miles
Test range: 163 miles
Shortfall: 33.1%
5. Make and model: Volvo XC40 Recharge Twin Motor Plus
Official range: 331 miles
Test range: 252 miles
Shortfall: 29.9%
6. Make and model: MG 4 Extended Range Trophy
Official range: 323 miles
Test range: 227 miles
Shortfall: 29.7%
7. Make and model: Volkwagen ID 7 Pro Match (with heat pump)
Official range: 381 miles
Test range: 268 miles
Shortfall: 29.6%
8. Make and model: BYD Dolphin
Official range: 265 miles
Test range: 188 miles
Shortfall: 29.1%
9. Make and model: BYD Seal
Official range: 354 miles
Test range: 255 miles
Shortfall: 28.0%
10. Make and model: BMW i5 eDrive40 M Sport Pro
Official range: 338 miles
Test range: 253 miles
Shortfall: 25.1%
11. Make and model: Tesla Model 3 Long Range
Official range: 390 miles
Test range: 293 miles
Shortfall: 24.8%
12. Make and model: Mercedes-Benz EQE 300 Sport Edition
Official range: 380 miles
Test range: 300 miles
Shortfall: 21.0%