16.10.2019Nissan Leaf e+ on the WLTP Challenge
Everyone knows that fuel economy figures and electric driving ranges are unrealistic right? Well, with the phased implementation of the WLTP (Worldwide Harmonised Light Vehicle Test Procedure) over the last couple of years, that statement should no longer ring true.
Granted, WLTP tests are still carried out in laboratory conditions, rather than using portable measurement systems during real-world driving. While this means WLTP won't return as accurate figures in terms of emissions and efficiency scores, it does mean that comparison between different models is easier.
The issue is that few have a handle on how accurate WLTP figures are. Will a petrol car that does 50 MPG or an electric vehicle that covers 200 miles on a single charge actually meet those figures? Or are these still inaccurate, just to a different degree to the previous NEDC-derived figures?
Fleet World decided to find out. Modifying its established and respected MPG Marathon, the WLTP Challenge was born. The aim is to see how accurate fuel and energy economy figures are in real world driving.
Next Green Car was invited along to take part, and handed the keys to a Nissan Leaf e+. It's a car we’re familiar with and the 62 kWh model's extended range over standard 40 kWh Leaf looked as though it should cover the route without the need for charging. A fair chunk of motorway driving before returning to Bristol via the Cotswolds meant it wasn't a particularly confident estimation however, so the charging element of the trip would have to be played by ear.
We were briefed to drive 'normally', rather than with a focus on efficiency. Taking in a 200+ mile route from Bristol to Birmingham and back via some waypoints, the challenge looked to simulate what might be found in a working day. A mixture of all types of road were included, with a good range of speeds factored in.
Starting at ALD Automotive's new base near the M4, we were given a route to reach RAC's headquarters in Bescot - a familiar sight for anyone that's passed Birmingham on the M6. To make sure we didn't just run up the M5 all the way, a coffee stop was included at Tewkesbury, and a waypoint had to be reached near Kidderminster.
Putting the first way-point in the sat-nav, I set the route to Eco mode, before realising that it was going to take me just about as short a route as possible to Tewkesbury. While that was best for an efficient drive, it would have taken around half an hour or so more to get to the stop.
Not only was the challenge supposed to be a test of a realistic driving route in a day - and getting from Bristol to Tewkesbury via Stroud isn't a reasonable representation of that route - but there was also a clock to beat. This sort of travelling at slow speeds would fall behind and drop out of the challenge.
As such, I compromised, and set off on the Eco route, before changing tack somewhere near Chipping Norton and setting up a Fast route. This saw me cut a corner off but not lose much time, and I joined the M5 at Junction 14, rather than where it meets the M4 at Junction 15.
I arrived behind a few cars but ahead of plenty, largely sticking to speed limits where possible, and driving to conditions otherwise. On the motorway, I sat between 65 and 70mph, conscious that I had a fair way to go still during the day, and also that the M5 from Bristol to Birmingham is effectively one long climb.
A quick pit-stop for the driver rather than the car saw me get back in to the Leaf with an efficiency score of 4.0 miles per kWh. For mathematical simplicity, I was working on a battery capacity of 60 kWh, and 4 x 60 is 240 miles on a charge. It was encouraging, and I set off for the RAC building more confident in being able to easily complete the route than when I started.
Having travelled up the M5 to the north of Worcester, and then coming off to join the Kidderminster road (A449) to make the way-point, I rejoined the M5 at Junction 3 Halesowen. From there it was a short and surprisingly easy run to Bescot, with traffic moving as freely as it ever does around Birmingham.
Some average speed limits were helping my cause, and I arrived at RAC with 58% charge remaining, having covered a little under half distance. Although I was more confident than at the start at completing the trip on a single charge, I decided that I'd top up a little at the fast chargers installed at RAC regardless.
Since this was supposed to represent a working trip, and I was stopping for lunch anyway, there was no issue with me - or any of the other electric car drivers - at plugging in en route. Leaving Bescot with both the car and myself topped up - me, a considerable percentage now made up of Chicken Satay, and the car's battery now sitting at 69% - the next leg was to head to Coleshill.
Here we were stopping for another quick pause and drinks stop, which wasn't really necessary having only driven from one side or Birmingham to the other. We were there to visit Airmax Remote, which were providing the vehicle tracking systems for the challenge.
Onwards from Coleshill was a route into the Cotswolds to Lower Slaughter for a final drinks stop before the homeward leg. By this stage, the Leaf e+ was displaying a range of 94 miles estimated, from 39% charge remaining. I knew that I wouldn't need to stop again for a charge as I crossed the rest of the Cotswolds, via Cirencester and Tetbury, before returning to ALD.
In fact, I returned with a projected 45 miles of range remaining and 18% battery. Even if I hadn't added the 11% charge over lunch, I'd have still returned with 7% - which I'd have been comfortable with doing.
The final efficiency score was 4.1 miles per kWh, which is the all-important figure. This is the one used by the organisers to see how the Leaf e+ performs compared to the WLTP figures.
Nissan's official WLTP range for the Leaf e+ is 239 miles with an energy efficiency figure of 180 Wh/km. These don't quite match up as converting the figures see 18 Wh/km switch to the more conventional 18 kWh/100km. Dividing the 62 kWh battery by 18 (kWh) sees 3.44 sets of 18 kWh/100km possible from the Leaf e+, or a range of 344.4 km on a charge - 214 miles.
However the official figures are worked out, my final figure of 4.1 miles/ kWh gives a range 254 miles on a charge. Calculating the range on the battery's charge sees a figure of 220 miles returned. That's having covered 205 miles on 93% battery - discounting the 11% topped-up - (205/93) x 100. There's a discrepancy, but working off the car’s trip computer figures, that's to be expected.
Whatever the method of calculating range - off an efficiency score or using miles over battery percentage - the conclusion is the same; it's perfectly possible to match, and even beat, the WLTP range quoted for the Nissan Leaf e+. I fell around 19 miles short of the official figure, but hadn't been driving any more efficiently than I would ordinarily have done in an EV.
Having tested a number of electric vehicles with WLTP ranges, we've come to the conclusion that the official results are a perfectly attainable figure. In real-world conditions, you might get a little less range, but the vagaries or weather and how heavy your right foot is or journey type can account for that. In the most part, if an EV says it will do 200 miles on a charge, you can reasonably expect 200 miles to be achievable.
As a note, the weather for the event was pretty typical of an early October day. The temperature was in the low-teens Celsius throughout, and the weather ranged from sunny to rain and everything in between. The range calculated isn't going to be achievable on a snowy winter's day in January, but equally it could comfortably be bettered on a warmer day in summer. As days to test out an average range figure, it was a good one.
So Nissan's Leaf e+ is able to get close to its WLTP score without any real effort. I'm an experienced EV driver, but was driving normally for an EV; reading the road ahead and using as much brake energy recuperation as reasonably possible. However, I certainly didn't sit at 55mph on the motorway or 40 along fast A-roads just to achieve a good result.
I was also the first back to base, helped a little by not having to come back via the petrol station up the road. Returning around 10 minutes ahead of the next car - a Skoda Superb 2.0 TDI diesel - shows that the route was completed in a good time too, without hanging back for an improved range. Should I have wanted to, I'd be able to get more out of the Leaf e+'s range with more careful driving and still arrive in time.
As such, the event has reinforced my reckoning that WLTP testing returns an accurate range for EVs. There are days when the EV will fall below the WLTP figure, but then there should also be days when you could beat the official range - something that couldn't reasonably be said about NEDC results. Therefore, if you are looking to buy an EV, you can expect the quoted range to be a realistic target.