July 25, 2023
Understanding range
Range has almost become synonymous with electric cars, as both the reason why people are most worried about (known as ‘range anxiety’) and also the way of measuring attractiveness and suitability when considering getting behind the wheel of an EV.
In the internal combustion world, you might be interested in engine size, performance figures, and other traditional indicators, but it is unlikely that you’ll judge a petrol or diesel car by how many miles you can travel before needing to refuel. In EVs, however, ‘refuelling’ is somewhat less straightforward and it takes more time to ‘gain range’ (i.e. top up your fuel level).
Therefore, knowing what the electric car is capable of between charging points becomes extremely important, and prospective owners look to range figures as opposed to battery size.
So, with range as the all-important metric, you may ask if you can just look up the range figure for an EV you're interested in and know that this is what you'll get.
Sadly, not quite. The issue with using range as an objective measure is that it is heavily influenced by external factors; the big ones being temperature and driving style. (See our article on maximising electric car range) That said, official range figures can still be useful to get a feel for what a car is capable of and how that compares to other vehicles, even if you can’t expect to achieve the official range figures in the real world.
WLTP
Since 2017, in the EU, official efficiency testing has been completed under the World Light Testing Protocol (WLTP), which replaced older testing methodologies that were particularly inaccurate when trying to measure electric vehicles. The WLTP electric vehicle range test involves assessing the driving range of an EV by simulating various driving conditions, including different speeds, accelerations, decelerations, and ambient temperatures. The test is conducted on a dynamometer, which is a device that simulates real-world driving conditions in a controlled environment.
During the WLTP test, the EV's battery is fully charged, and then the vehicle is driven on the dynamometer according to a defined driving cycle. The driving cycle consists of different phases, such as urban driving, rural driving, and motorway driving. Each phase has specific parameters for speed, acceleration, and deceleration. The test takes into account factors that can affect range, such as air conditioning or heating usage, auxiliary power consumption, and rolling resistance.
Despite the scientific merit in creating a fair, identical test every time a vehicle goes through the process, the major limitation of WLTP is that it is completed in a laboratory. As a result, the aforementioned external factors are excluded from the estimates, and the general consensus across the sector is that the WLTP rating is overly generous to the tune of 15-20% on average (which is when you’ll hear people talking about the ‘real-world’ range).
The ClearWatt approach
Across the suite of products offered by ClearWatt, a common and unique approach has been taken which explicitly seeks to measure range in real-world conditions. These figures have been calculated and gathered from a number of sources, including an AI-driven vehicle simulation model commissioned from a leading academic partner, crowdsourced experiences from the international EV community and of course real-world testing via the EV Health Checker BETA programme. To see our unique real-world figures for brand new EVs, please take a look at our Directory section.
Going somewhat further than this, the ClearWatt app grades the real-world range capability of a specific vehicle rather than just an expected average for a brand-new model of car. We achieve this by actually measuring energy consumption as journeys are undertaken whilst gathering data on all of the external factors that may be influencing that efficiency score, which our industry-leading algorithm is then able to account for and adjust for.
