The EV Revolution

Premise

The first time I came across the EV domain dates back to early 2000s. My team and I had worked on the engineering development of a family of vehicles and were asked by our customer to work on a zero-emission, full electric vehicle feasibility study. That request was strictly connected to a law that was supposed to come into force in California, allowing only ZEVs (Zero Emission Vehicles) sales of in the future. There was no subsequent coming into effect and, at that time, I thought the transition towards zero-emission vehicles was not expected to move fast.

About ten years later, I had the opportunity to analyse and drive a Tesla Model S. As Italdesign was a traditional coachbuilder, our approach and standpoint were rather sceptical. Lines were too simple to us; there was inaccuracy in the treatment of details, whereas we were used to their being meticulously treated in premium cars; wide and irregular gaps between parts; couplings between visible parts that could be improved and a general feeling of lack of robustness.

Then, the time came to drive the car and my user experience was something definitely new, something I had never experienced before.  Acceleration, not just from standstill but at all speeds, decidedly superior compared to acceleration in sedans of the same class using internal combustion engines (ICE). I’d say racing and motorsport-wise, to describe it.  A wide screen right in the centre of the dashboard to control all functions of the car, including window lifters and climate control vents, so no buttons or levers in the passenger compartment. Intuitive and simple to operate; no complex navigation system, but a simple connection to Google Maps; a driving assistance system that was not as reliable as I expected, but avant-garde for that time indeed. What seemed at first glance to be a lack of contents, later turned out to be a new concept of car, where simplicity of use is the true richness of the product.

After a journey of about 80 kms, I had to charge up: the time for having a coffee and a chat at a Tesla supercharging station and in less than 45 minutes the car was ready to drive back to Turin.

After this unexpectedly positive experience on board an electric vehicle, I had no other opportunities to cross my professional and user life with such products for a while. Regulations related to electrification, though, were ready to take effect in the years to come. Moreover, the shift of large parts of the markets towards electric cars in important countries such as China or the United States, has brought to the fore electric cars, with which I’m now daily in close contact.

“It isn't a given that the companies that provide mobility today will also be the ones to do so tomorrow. Every company has to work hard to make this happen.” Norbert Reithofer– Former BMW CEO

In this article, I will speak about my professional and private user experience related to Vehicle Electrification.

The EV revolution: the engineering approach

Conversion of vehicles with internal combustion engines (ICEs) to electric cars was my first task in the engineering development of BEVs (Battery Electric Vehicles). If, for some aspects, the integration of an electric traction system simplifies the development of a car, for others, it makes it more complex.

Installing an electric engine doesn’t cause any complications, as it has a smaller volume than an internal combustion engine. Aspects related to acoustic insulation are simplified since there is no longer need to 'protect' occupants from experiencing loud engine noise. Thermal management is trouble-free too, as there is no need to dissipate the heat generated by the internal combustion engine but to cool down the batteries, which is somehow less problematic than cooling an ICE. This allows for simpler thermal management systems and for new ways of designing a vehicle, without needing large air intakes at its front. An aspect that also improves aerodynamic performance, with a consequent increase in a car's range.

Installing a battery in a car converted to electric is of course a compromise with the vehicle architecture. The battery needs to be installed in place of the fuel tank and in the spaces available in the central floor, such as the tunnel where there is no longer any need to place an exhaust pipe, or the area under the front seats (Fig 1a). This sets limits in terms of battery volumes and therefore in terms of the autonomy of the car itself. The protection of the battery pack in the event of a crash was a first important evolution in the engineering approach of integrating the electric traction system. Damage to one or more cells due to compression or deformation causes a rapid release of energy, with a consequent increase in temperature and fire ignition. In the event of an accident, compared to a car with an internal combustion engine, the permissible deformations on the floor under the passenger compartment must therefore be significantly smaller in order not to damage the battery. This requires reinforcing the central body structure. Furthermore, dimensioning load cases, such as pole impact, which simulates a collision of the car against a tree in the event of going off the road, or impact with some parts of the road, such as the edge of a sidewalk which could damage the battery in its lower part, are more relevant for the battery and, therefore, occupants’ protection.

At the same time, in the event of a front-impact car accident the occupant protection has been simplified, having greater space for deformation in the engine compartment to absorb the energy of the impact and being the intrusions caused by the engine decidedly reduced, thanks to the smaller dimensions of the electric motor compared to the thermal one.

The development of a 'native' BEV car allows for the installation of the battery in an optimised structure architecture, occupying the volume of the central floor under the occupants in the best possible way (fig 1b). In the event of an accident, the issues of battery protection from deformation, to avoid triggering fires do remain, but the current battery cases and use of structural profiles in the body solve this problem.

The increase in weight due to the battery and its protective structure brings about an overall increase in vehicle weight, with a consequent reduction in the range.

The adoption of solutions to reduce vehicle weight, as well as aerodynamic shapes, become therefore necessary, even more fundamental than in the past.

In terms of weight, the adoption of lightweight materials, such as aluminium, for the bonnet, tailgate and doors or for the entire body structure is increasingly common, even for low-segment cars.

The study of shapes and aerodynamic solutions determine different body styles of vehicles, with more 'streamlined' rears, 'closed' fronts (thanks to the lower need for air flows in the engine compartment, since it is no longer necessary to dispose of the heat generated by the internal combustion engine, as described above) and flat bottoms under the car, thanks to specific underbody covers.

In addition to the aerodynamic performance, the aeroacoustics performance (noise generated by external air flows in the form of hiss and whistles) and the acoustics in general in the passenger compartment are managed in a different way in electric cars. When compared to internal combustion engines, the reduced electric engine noise, may seem like a simplification in providing occupants with a comfortable travel experience, but this reduced noise must be managed. There are other sources of noise that can become significantly disturbing, such as the cited aerodynamic noise but also the rolling noise of the tires or small structural squeaks and rattles. It is therefore of major importance to acoustically isolate the area of the floor around the wheels, as well as designing the plastic parts of the passenger compartment avoiding relative micro-movements of the components with adequate fastening systems and elements that act as shock absorbers between the parts.

The absence of engine noise and vibration can also lead to confusion and dangerous situations. When turning the engine on, the driver does not perceive vibrations and does not hear noises, thus giving the sensation that the car itself is not turned on and ready to go. Similarly, road users have no way of hearing electric cars approaching, because of their being so quiet. Artificial sounds are therefore introduced to give the driver, inside a car, the sensation of ignition of the car, and to road users, outside the car, the information that an electric car is on the way.

Specific features are introduced in sports versions, which allow users to set the noise inside the passenger compartment, having available, in sport mode, the typical noise of a high-power sports engine which, combined with the performance of the electric motor, allows to enjoy a normal sedan as if it were a super sports car.

"Change is the law of life. And those who look only to the past or present are certain to miss the future." John F. Kennedy– Former USA president

The different architecture of the central floor, without the tunnel for the exhaust pipe, allows the creation of different interiors structures, freeing up space in the passenger compartment with a full flat floor. The centre console can have new shapes, thanks to the available space, featuring futuristic styles shaped like bridges or with cantilevered controls. This requires adequate sizing to avoid phenomena of vibration or damage in the event of misuse, such as, the passage from one front seat to another, leaning on the structure itself.

For the rear passengers, ergonomics is improved thanks to the greater space available for the feet in the central area, where no tunnel for exhaust pipe is needed.

Finally, the set-up of suspensions for the driving feeling changes due to the low centre of gravity of the car and the mass of the batteries under the floor. This determines greater vehicle stability and an overall safer driving sensation.

In conclusion, engineering an electric car is not reduced to a simple replacement of a combustion engine with an electric one and a tank with a battery, but has various implications from the vehicle architecture, performance and contents point of view. This requires new approaches to the car development process and an adaptation of expertise in acoustics, aerodynamics and general exterior and interior design and validation.

An adaptation that needs to be continuous and fast: we already known for example, that current battery concepts will evolve and feature new architectures with a reduction in terms of volumes and an increased efficiency. Batteries including cell modules are already evolving into batteries without any modules, but with cells directly assembled to form the battery itself (cell to pack). And systems in which cells will be assembled directly on the vehicle (cell to vehicle) (Fig 2). are already being developed.

The EV revolution: the user approach

In addition to the experience from an engineering point of view, I am lucky enough to be able to drive both hybrid and electric cars., which enables me to better understand, also as a user, what are their peculiarities in their daily uses.

As above mentioned, the first difference is felt when starting the car due to the absence of engine noise or vibrations. If we are not used to it, we can doubt the car is on. I am not ashamed to say that in the early days of use of EVs I turned the car off and on again to double check it was on.

Depending on the model, when the car starts moving, it is possible to hear, a constant background noise generated for external users, however, from an acoustic standpoint, the experience is decidedly more muffled than on board ICEs.

When your journey begins, you can appreciate the different reactivity of the electric motor, always ready for a sports car acceleration at all speeds. The sensation of driving a car with decidedly superior performance to those around you, with the possibility of being able to accelerate and easily overtake other cars arises. In short, you can enjoy a sensation of sportiness typical of videogames.

Clearly, performance is paid for in terms of range: driving styles and habits determine variations in the estimated total range. Driving in a city, with low accelerations and low constant speeds, allow you to guarantee up to 30% longest ranges than a sporty or high-speed way of driving on a motorway. But the type of road can also in a way affect your range, which is why systems are being created to estimate the distance that can be covered according to the traffic and the profile of the road, considering, for example, the gradients, and not only according to the battery charge level and the consumption estimate based on the last km driven (Fig 3)

Autonomy is undoubtedly one of the most debated issues among users and non-users of electric cars. The recharging times are unquestionably slower compared to refuelling ICE cars and the driving range is generally shorter. But the gaps are closing very rapidly. I personally drive both a BEV car and an ICE of the same class: they differ in range for about 100 km, but we must consider that the range of electric cars is rapidly increasing in the new models. Short-distance travels are not problematic in terms of ”charging anxiety”; on the contrary, the need for planning long-distance travels in an EV is highly sensible  and the discomfort compared to ICE cars is still considerable. Not just for the charging times, but also for the availability of chargers. So, I must admit that, over long distances the solution I personally prefer is still the hybrid car.

To increase autonomy, there are traction release systems in the deceleration phase but, above all, energy recovery systems via the brakes. When the accelerator is released, the car brakes autonomously, recovering the braking energy and converting it into electricity to recharge the battery. And this, together with acceleration and the possibility of sporty driving, is the second element that most influences and changes driving style. You quickly get used to looking for ways to limit energy consumption and, in fact, you tend to drive by limiting the use of the brake as much as possible, relying on energy recovery braking, therefore acting almost exclusively on the accelerator. Over time you almost tend to challenge yourself in minimizing consumption, with an inner satisfaction when you realise you did not pollute during your journey.

"Before you say you can’t do something, try it."  Sakichi Toyoda – Founder of Toyota Industries Company

Finally, the spaces inside the passenger compartment and in the trunk present new features. A large storage compartment in the lower part of the central console makes the car spacious and liveable, when you want to store objects, such as your telephone, wallet, or keys, while the roominess of the rear seats, as already mentioned, is increased by the space available for the feet of the central passenger.  Things are different when we talk about the trunk, where the presence of cables can be painful, especially when the compartment must be fully loaded with luggage. However, we quickly get used to managing cables and their storage.

To sum up, driving an electric vehicle is definitely a different experience compared to driving an ICE: I personally think it is much more fun and engaging.

Conclusions

The advent and growing importance of electric cars pose new challenges to people like me, who work in the automotive engineering but also, and above all, to vehicle users.

There is still a long way to go to have the electric evolution accepted by consumers. The production processes, it is known, to date are such that the CO2 emissions in the production phase of an electric car are higher than that of an ICE. A breakeven point for emissions is reached between 80,000 and 120,000 km, provided that clean electricity is mainly used.

Electric cars have a sticker price 25-40% higher than traditional ICEs, on average, making them not easily affordable.

Charging infrastructure is one of the main barriers to EV market diffusion: in large cities, areas where to charge EV cars are limited, as well as along motorways. To date, unfortunately, the speed of evolution of the electric car product is still decidedly higher than that of the necessary charging infrastructure.

There are however examples of markets where the introduction of electric cars is successful. Just think of China where, in large cities, it is possible to see a constantly growing fleet of electric cars. I personally had the chance to meet Chinese users of electric cars and they all said they were enthusiastic. The cost difference to buy an EV compared to an ICE car in China is minimal thanks to state investments and industrial planning for the development of electrified transport. Maintenance is negligible and the lower charging costs compared to fuel make the out-of-pocket cost of the car cheaper.

Although there are still aspects that generate distrust and resistance of part of the users, I am convinced that in a few years the still existing gaps will be filled in. Battery capacity and therefore vehicle range grow at a rate of 100-200 km every 3-5 years, charging times drop by 20-30% every 7 years. Prices of EVs fall less rapidly than the increase in technology but still steadily.

But the real change will be in the availability of charging stations. I can personally witness that, having the possibility to charge, either at home or when I’m at the office, battery charge in standards use in the city is no issue at all. But when I put myself in the other person’s shoes who do not have this opportunity, I understand it is not fun at all. When recharging stations and chargers will be available in adequate quantities and locations and there will be no need to wait for the charge because, in the meanwhile, we’ll be working or shopping or simply relaxing at home, then the electric car will no longer be an object of scepticism and resistance but will become an object of desire for car enthusiasts.