Fleet operators not only need to minimise costs but also ensure their drivers are safe and have a driving environment that minimises stress and distraction.
Nissan have just launched a new variant of their recently released X-Trail mid-sized SUV. It has a hybrid power train that is different from others and while not achieving class leading fuel economy, Nissan says it is designed to make the driver feel more at ease with the car.
Why is this hybrid is different?
The typical hybrid drivetrain, design as brought to the mass market by Toyota starting with the Prius, is to have an internal combustion engine (ICE) powering the wheels through “normal” vehicle gearboxes with some help from an electric motor. In the case of Toyota and some other brands the vehicle can operate on electric power alone, but only for a short distance.
Some brands have introduced mild hybrids where the electric motor has an even smaller role to play, and some hybrid trucks do not have an EV only capability.
Plug-in hybrids still connect the ICE to the driving wheels, but place more emphasis on the electric motor. Typically they can travel 30-60 kms on EV power alone, which is well suited to urban environments and reducing fuel costs especially when short trips predominate.
The Nissan approach is to drive the wheels only by the electric motors and use an ICE only to generate power for the battery.
This is similar in concept to the diesel-electric railway locomotive and very large dump trucks on mine sites (although in these cases they use a diesel engine).
In part it means that the ICE can be tuned to run more efficiently rather than having to have performance over a wide rev rang. Also the driver gets all the advantages of driving a vehicle that responds like a full electric vehicle.
The Nissan has two electric motors, one for the front wheels one for the back. The combined available power from the twin motors is 157kW. The battery is a relatively small 2.1 kilowatt hours.
Nissan does sell a two-wheel drive, single electric motor variant overseas, but will only market the e-power X-Trail with its e-4ORCE all-wheel drive in Australia.
The internal combustion engine that generates power for the battery is a 1.5L turbo-petrol 3 cylinder motor. The e-POWER does vary the revs to a reasonable extent and its efficiency is assisted by incorporating variable compression ratio technology.
There is no point in having a bigger battery if the ICE can generate enough charge. Nissan say that they have tested the X-Trail is a very wide range of situations under heavy acceleration and steep hills and including towing to its maximum rating of 1,650 kgs.
Why not build an EV, or traditional hybrid?
Is there really much difference in driving a vehicle where the power is delivered to the wheels only by electric motors? At the launch, Adam Robertson from the Nissan Technical Centre Europe located in the UK, described why they took this path.
“If you remember we were the first to market with a mass market, the Nissan Leaf. So over ten years ago, 2010, 2011 we listened deeply to those customers, and we studied what they were saying and actually they were really, really happy, really satisfied with the acceleration of the car,” explained Robertson.
“Now it wasn’t an outright acceleration performance. It’s not, you know, we see some of the EVs now 0 to 60 [MPH] in under the 3 seconds. We’re not talking that, we’re talking with original Leaf. And when we started talking about, it’s more about the responsiveness and the smoothness of the acceleration in the real world in day-to-day life.
“So pulling out onto that busy roundabout on the school run with a small gap in the traffic in an EV is fantastic. Put your foot down you go, and you haven’t got to wait for transmissions and engine revs etc. before you can pull away. Looking at the data, satisfaction for acceleration was very, very clearly the highest. Then petrol and diesel, then [traditional] hybrid. So hybrid was last.
“So we wanted to bring that enjoyment, that EV driving characteristic, to those people that weren’t quite ready to make that transition to, plug-in and EV.”
There is growing feedback that suggests that while the immediate and strong response of the vehicle is appreciated, for many drivers it is not the supercar acceleration that has been part of Telsa’s image, and other vehicles trying to emulate this performance.
Firm, immediate acceleration when necessary as well as quietness and comfort are part of the driver’s environment. Mercedes Benz, for example, has recorded a marked reduction in the stress for their drivers in electric trucks compared to a diesel engine vehicle, with the reduction in vibrations and noise including engine braking.
The major benefits of Nissan’s approach are:
- Reduced noise environment including noise cancelling
- e-4ORCE delivers faster take off
- Linear engine tuning matches acceleration with RPMs, eliminating rubber-band feeling
- Constant torque redistribution and balanced weight distribution (F:51.8% R:48.2%)
- Dual regenerative braking from front and rear motors
- Stable acceleration and braking, with the vehicle remaining flat
- Torque distributed front or rear to maximise grip
- Up to 10,000 times faster torque distribution than mechanical 4WD systems
- One-pedal driving
The cargo area in the X-Trail Hybrid is only slightly compromised by the electric motor in the back. With the rear seats in the up position, it is rated at 575 litres only 10 litres less than the non-hybrid models.
Does it reduce fuel costs?
While the technology in the Nissan represents an advanced and interesting step, the rated fuel consumption is not class leading. The official combined figure is 6.1 l/100kms. By comparison the Toyota RAV 4 is rated at 4.8 l/100 kms. At the launch, Nissan said that they felt the e-power would show up better under real world conditions.
I think we need to pay more attention to the fuel consumption in city areas. Nissan admits that the X-Trail is likely to be used mostly in urban areas yet at the launch they did not have the urban consumption figure. Urban areas are where hybrids can perform significantly better than ICE only vehicles because they can recapture some energy through re-generative braking.
The governments Green Vehicle Guide rates the e-power e-4ORCE X-Trail and the equivalent ICE only model as follows:
| Hybrid e-4ORCE | ICE | |
| Combined | 6.1 | 7.8 |
| Urban | 6.5 | 10 |
| Non-urban | 5.8 | 6.5 |
Nissan’s step into hybrid drivetrains with their X-Trail, represents technology that is interesting and advanced. The fuel savings are not as strong as would have been hoped for, but it is better than just an ICE model especially in urban areas. The less stressful driving environment is a plus for drivers.
Nissan see this hybrid as a stepping stone to fully electric vehicles. It has certainly raised a broader consideration of potential consequences of electrification, beyond pollution reduction and frenzied straight line acceleration.
