How to solve the problem of difficult parking for electric vehicles through technical means

The three most difficult things about buying a car are the down payment, monthly payments, and parking.

In first- and second-tier cities where land is more expensive than human skin, parking is annoying for everyone. Whether you have a groceries car worth hundreds of thousands or hundreds of thousands, or a luxury car worth tens of millions or millions, the inverted duck and the concrete wall are of no concern. Drivers who have had the painful experience of parking will pay more attention to the width of the car body when changing cars.

Unfortunately, at first glance, it seems that the only difference is the powertrain. When it comes to maneuvering in a small area, electric vehicles actually have a natural disadvantage. This disadvantage can be compensated by technical means, or it may be more or less exposed. For some pure electric models, the difficulty of parking may not be an illusion.

I got stronger and bigger

Today's cars are getting bigger and bigger, which is not surprising. It has been like this since the birth of the car. Whenever long-standing models such as the Porsche 911 and MINI are placed next to their ancestors, the expansion of the size of cars over the past half century is obvious.

In terms of size increase, especially lateral width, pure electric vehicles as a whole have shown a more positive and enthusiastic attitude and status quo compared to fuel vehicles. When the body length is similar, electric vehicles tend to be relatively wider.

For example, in the mid-size car class, the typical exterior dimensions of the three BBA mid-size cars range from 4728 to 4762mm in length, and the corresponding body width ranges from 1820 to 1827mm (only the A4 is 1847mm). All data are based on the standard wheelbase version, excluding the width of the rearview mirror.

Compared with the three competing products of BBA, Model 3 has the shortest length of 4694mm and is obviously smaller than the three fuel vehicles, but its width of 1850mm is the largest among the four. In other words, when viewed from the roof, Model 3 is the most "square" among them.

The figure shows the width including the rearview mirror

If the Model 3 is not obvious, the length range is slightly longer than the BBA standard wheelbase mid-size cars, the Haibao and ET5 (4800mm and 4790mm), and the width reaches 1875mm and an astonishing 1960mm respectively. This is equal to or even exceeds the BBA mid-to-large cars.

In the mid-to-large car category, the widths of NIO ET7, Zhiji L7, Zeekr 001, and Nezha S are 1960-1999mm, and the narrowest Mercedes-Benz EQE and Leapmotor C01 are just over 1900mm. In the world of fuel vehicles, the typical widths of the E-Class, 5 Series, and A6 are still "remaining" at 1860-1880mm.

For new pure electric platforms, there is no need to consider the internal combustion engine, so the four wheels can be pushed as far as possible to the four corners of the vehicle body, and the ratio of wheelbase to vehicle length, i.e., the axle length ratio, is usually larger. This is clearly reflected in the Mercedes-Benz EQS/EQE and smart #1, where the wheelbase is 100~200mm longer than that of fuel vehicles of the same length.

Of course, not every electric car will necessarily be wider and have a longer wheelbase than every fuel car. And as fuel cars are updated, they may continue to become wider in the next few years, just like the example of the 911 above. Things are always developing dynamically.

But as a whole, the more newly launched and high-end electric vehicles are, the more obvious their tendency towards larger width and larger wheelbase ratios; compared with contemporary fuel vehicles, electric vehicles tend to seek wider body widths and are more likely to choose relatively larger wheelbase lengths.

And we know that under the premise of the same body length - discussing flexibility obviously requires controlling the size level variables, pure electric vehicles (relatively speaking as a whole) have wider bodies and longer wheelbases. These are not conducive to reducing the turning radius and improving flexibility.

For example, a new car brand's mid-to-large sedan without rear-wheel steering has a width of nearly 2 meters and a wheelbase of 3.1 meters, which creates a minimum turning radius of 6.3 meters. This means that it is almost inevitable that you will not be able to make a U-turn on most urban two-lane roads that are less than 3 meters wide.

Bigger and more expensive, so more krypton

A larger wheelbase ratio is a benefit of electric vehicles abandoning internal combustion engines, but it is not necessary. So when the advantage of the wheelbase ratio of electric vehicles is used to achieve a long wheelbase, which inevitably compromises flexibility, the choice of a larger width can only be due to other factors.

Safety is easy to think of. The importance of battery safety is self-evident. The front and rear of the car have a certain buffer space, but the impact from the side is closest to the battery. In fact, this is the same as passenger safety. The side collision without buffering is always the most likely to cause harm. In order to prevent side collisions, electric vehicles generally use a wide side sill beam structure.

Xiaopeng G9, gray door sill beam uses extruded aluminum profile

Thicker sill beams are also a typical feature of the body-in-white structure of electric vehicles. The sill beams and the battery side buffer structure occupy a certain width, and the internal passenger space and battery pack width must be guaranteed - the latter determines the power and endurance. Therefore, the overall width of the electric vehicle tends to reach the maximum value under the existing possibility.

Width increases, wheelbase increases, but if the maximum deflection angle of the front wheels can be increased, the turning radius may not increase, and the low-speed flexibility level can be maintained. However, the inherent structure of electric vehicles determines that they are not easy or suitable for doing so.

In the past, it was generally believed that since electric vehicles do not have internal combustion engines, the front cabin space is freed up, and the left and right deflection space for the front wheels should be larger. However, in some electric vehicles, the front longitudinal beams are moved further to the sides, and the central motor does not fully utilize the space between the longitudinal beams, while the deflection space left for the front wheels on both sides is reduced.

Lucid Air, there is still a lot of space on both sides of the front motor

In order to improve collision safety, the front longitudinal beam of the fuel vehicle era can directly transmit energy to the multiple longitudinal structures arranged at the bottom of the vehicle. In electric vehicles, since a large area in the center of the chassis is occupied by the flat battery pack at the bottom, the energy of the front collision needs to find another way to transmit it backwards.

For example, the side sill beams are already thicker, and some electric vehicles direct the collision energy from the front longitudinal beams to the side sills. To make the energy conduction along this path as efficient as possible, the front longitudinal beams at the front of the vehicle need to be as close to the sides as possible, but this will naturally compress the space left for the front wheels to deflect left and right.

NIO ES7

Energy conduction path of fuel vehicles

This feature is more common in high-end electric vehicles. In addition to collision energy conduction, high-end cars need to pursue high body rigidity in order to pursue better NVH and driving quality. A large torque-box made of cast aluminum is used between the front longitudinal beam and the side sill beam, which allows the side sill beam and the front longitudinal beam to share the load from the front wheel.

ES6

I-PACE

In order to improve the performance of the vehicle body, the front longitudinal beam is moved to both sides. The large size of high-end vehicles makes the flexibility worse. The front wheel deflection angle cannot be increased or even limited. Therefore, the rear wheel steering system RWS has almost become the standard and symbol of large-size high-end electric vehicles. Although fuel vehicles are also enlarged and use RWS, the demand for electric vehicles is particularly urgent.

Mercedes-Benz EQE has a wheelbase of 3120mm and uses up to 10° rear-wheel steering to achieve a significant improvement in the minimum turning diameter from 12.5 meters to 10.7 meters. Zhiji L7 has a similar wheelbase but a wider car. The 6° rear-wheel steering (12° left and right in total) reduces the turning diameter by 1.3 meters.

It can be seen that the EQE's 1906mm width is considered narrow among electric vehicles of the same level, and it still relies on the existing 4.5° rear-wheel steering before the upgrade to achieve a turning diameter of 12.5 meters/radius of 6.25 meters, which shows the pressure that only front-wheel steering faces. Due to the structural characteristics of electric vehicles, RWS is likely to become an indispensable business card configuration for high-end electric vehicles in the future.

Automobiles are a systematic project, with one link after another, affecting the entire system. High-end cars that are not too concerned about cost can get rid of certain weakening tendencies caused by the structure of electric vehicles by spending money, so that the tendencies remain just tendencies. Rear-wheel steering is the hardware foundation, and there is also a life-saving straw that someone will definitely think of, automatic parking.

The physical existence of the vehicle body width still needs to be rescued by the follow-up of infrastructure standards. In some first- and second-tier cities, narrow parking spaces are not uncommon, and the vehicle body width is nearly two meters without rearview mirrors. Perhaps only functions such as automatic summoning can partially make up for it.