LEAF Turns to the 2020s

Nissan’s pioneering battery-EV finally gets styling, propulsion and feature upgrades that put it back in the thick of the expanding electric-car race.

February 1, 2018

Lindsay Brooke

The 2018 Leaf carries over much of the outgoing car’s underbody but adds a new battery pack and cells that are more energy-dense. (Credit: NISSAN)

Seven years is nearly twice the duration of a typical automotive product cycle, but it’s been that long since Nissan turned a new Leaf. The original 2011 Leaf boldly pioneered 5-passenger practicality with nearly silent, zero-tailpipe-emission driving. Its operating range on a single charge, about 75 mi (120 km), suited some commuters (and the EV faithful) in thermally-ideal regions such as California. Drivers in colder climes, however, often faced the dilemma: “Do I run the heater or make it home on the rapidly-dwindling charge?”

Then came Tesla’s Model S and the humble Leaf, despite a modest upgrade in range, got raked back-stage amid Ludicrous-mode hoopla. Last year Nissan sold just 10,000 Leafs in the U.S. and it took until January 2018 for the car’s six-year global sales total to reach 300,000 units. That makes Leaf the world’s EV sales king, but battery electrics outside the Musk halo find it tough to earn mainstream converts. Globally they account for about 0.5% of passenger vehicle sales. In the U.S., the low retail price of hydrocarbon fuels isn’t helping the ZEV cause, either.

Nissan engineers almost achieved mass parity with the 2017 Leaf via thorough FEA work on the steel-intensive structure. (Credit: NISSAN)

But with CO₂ and greenhouse-gas regulations set to tighten further during the 2020s — and more nations ruling to outlaw new non-electrified vehicles — experts expect battery-EVs to steadily gain share, albeit more slowly than hybrid-ICE models.

Engineering VP Chris Reed noted significant reduction in cabin noise. (Credit: Lindsay Brooke)

The 2018 Leaf, now packing 150-mi (241-km) operating range, and with +200-mi (321-km) battery capability coming for 2019, will lead Nissan’s electric march into the new decade. It brings Nissan’s ProPilot Assist feature (see sidebar) that combines adaptive cruise control with lane centering for single-lane freeway driving — it won’t change lanes, however, and requires hands on the wheel.

Assembled in Japan, the U.K. and Smyrna, Tennessee, with mainly suspension calibrations separating the regional variants, the 2018 version is not ‘all-new.’ Much of the new Leaf’s underbody, 106.3-in wheelbase, and suspension (front struts, rear torsion beam) carry over from the outgoing model. But it’s a significant leap forward in nearly every static and dynamic metric except its 3,468-lb (1,573-kg) base curb weight that’s about 33 lb (15 kg) heavier than the old car.

Nissan engineers consider that an achievement, as will many SAE readers, who know the challenges in combating ‘mass creep’ in new vehicle programs. But Nissan’s thorough FEA work during Leaf body engineering helped extract about 110 lb (50 kg) from the structure. That’s impressive considering it is still steel-intensive (as are the closures), is reinforced at key points, and is 1.4-in (35 mm) longer and fractionally wider and taller, noted Chris Reed, Vice President of the Nissan Technical Center North America in Farmington, MI. The 2018 body is about 15% stiffer in torsion than the 2017 body, Reed said.

Lower Cd, more kW

EV Development Manager Owen Thunes said e-Pedal performance benefits drivers on steep hills. (Credit: Lindsay Brooke)

Reducing structural mass, aided by use of high-strength steel alloys in the sills and pillars, helped offset weight gains in other areas. Reed noted that upgrading rather than replacing the body structure, as well as cost reductions through various propulsion and battery improvements, enabled Nissan to aggressively price the new Leaf. The US$29,990 base price (before federal EV rebates) is about $700 less than the outgoing mode. The low pricing is a key to Nissan’s market strategy for its revamped EV.

Broadening the car’s visual appeal was important for hooking potential EV customers who don’t yet understand amps and kilowatt-hours. Nissan Design gave the new Leaf a contemporary exterior form that no longer “shouts EV.” The 0.28 coefficient of drag represents a 4% improvement over the first-gen car’s Cd, according to Reed.

The aero gains, along with greater attention to cabin sealing, help create one of the quietest cabins of any production car, Reed claimed. He said interior noise levels are reduced by more than 1 dB at 62 mph (100 km/h) versus the previous Leaf. Indeed, Automotive Engineering’s early test drive in late 2017 revealed outstanding interior noise attenuation with less gear whine evident, to our ears, under deceleration than on Chevrolet’s Bolt EV, VW’s e-Golf or the earlier Leaf.

Nissan’s program investment included a new permanent-magnet traction motor rated at 110-kW (147-hp) and 236 lb·ft (176 N·m) driving the front wheels. Still an EM57-type AC induction machine, it includes a new inverter and delivers 37% more power (30 kW) and a 26% gain in torque (49 lb·ft/66 N·m) versus its predecessor. With a final drive ratio of 8.193:1, the new e-motor helps make the 2018 Leaf about 15% quicker from zero to 60 mph, Nissan engineers said. AE’s 122-mi (196-km) test route of mixed driving (accomplished on a single charge) showed Leaf to be superb for squirting through traffic — and to be more confidence-inspiring in moderate-speed cornering than the ’17 version.

Nissan remains wedded to the CHAdeMO charging protocol and hardware. The new Leaf supports Levels 1-3 charging. (Credit: NISSAN DATA)

Driver engagement is enhanced with the standard “e-Pedal” mode. Like the paddle-controlled system on Bolt, Nissan’s provides a “one pedal” driving experience. “The combination of regen and friction braking offer up to 0.2-g decel capability,” said Owen Thunes, Manager, Engineering/EV Development. He claims the system will stop and hold the car on a 30% grade.

Packin’ more battery

Storing and supplying the ‘Leaf juice’ is a 40-kW·h battery pack that’s 33% more energy-dense than the 30- kW·h pack used in 2017. It retains the old pack’s passive air cooling and 192 prismatic-form-factor lithium cells. And its ‘footprint’ also remains the same due to improved cell chemistry. The new cells (still supplied by AESC) feature a new nickel-manganese-cobalt chemistry with a graphite anode. They are .9-mm thicker and use a thinner separator, to reduce internal resistance. They’re now bundled eight per module, 24 modules total, versus 48 modules of four cells each.

Leaf’s trademark nose-mounted charge compartment continues on the 2018 model. (Credit: NISSAN)

The new cell design and pack layout makes the 2018 Leaf fully competitive in range and power to other new EVs including Hyundai’s Ioniq Electric and the Honda Clarity EV, according to Thunes. And the 60- kW·h pack slated for MY2019 — which is expected to use prismatic NMC cells supplied by LG Chem, according to a battery-supplier source — should give Leaf range to challenge Chevy Bolt (~238 mi/383 km).

New Leaf interior features 7-in touchscreen and higher-grade tactile surface quality on more visible trim parts. (Credit: NISSAN)

Thunes said the new 40-kW·h pack, made at Smyrna, can retain 90% of its capacity after 500 charge/discharge cycles or over 60,000 mi. The 8-year, 100,000- mi (160,934-km) pack warranty carries over.

The new Leaf retains its trademark centrally-located charge port under a door on the car’s nose. Nissan adheres to the CHAdeMO DC charge coupler developed with its Tokyo Electric Power Co. partner rather than using the SAE ‘combo’ connector favored by most other OEMs except Tesla. Leaf’s on-board 6.6-kW unit offers 120-V and 240-V charging along with a Level 3 fast charge that can load 90 mi (144 km) of electrons in 30 minutes.

According to Nissan V2X manager Scott Brierley, the new Leaf has bi-directional charging capability. But its car-to-grid feature, which he said can deliver up to 6 kW from the car’s battery to a home for emergency lighting, for example, is not yet approved for U.S. use.

Inside Leaf’s cabin the driver is struck by good all-around visibility due to the high seat mounting. There’s a 7.0-in touchscreen centered in the IP and Android Auto and Apple CarPlay are now standard.

Also visible are more soft-touch surfaces but there’s still excessive hard plastic — a questionable cost saver in cabins, the author believes, as is the steering wheel that adjusts for tilt but does not telescope.

Small issues, perhaps, in a high-value EV that’s squarely back in the global electric-car race and appears to be engineered and fully equipped to deliver on its design goals.