Lotus Unveils Modular Lightweight Electric Vehicle Architecture For Two Sports Cars And Perhaps A 2+2 GT

Last week, Lotus unveiled its Lightweight Electric Vehicle Architecture, or LEVA, a highly modular and mutable battery-electric architecture that will serve as basis for two upcoming sports cars and potentially a 2+2 GT. To better understand LEVA, I reached out to Richard Rackham, Head of Vehicle Concepts at Lotus.

“The structure is fully adaptable to provide a platform for a range of EVs with variable layouts, wheelbase lengths, battery sizes and configurations,” says Rackham.

“As the animation shows, all three layouts feature a common lightweight rear end structure and suspension. This rear end structure can accommodate propulsion units of differing complexities and performance, single or twin motor,” says Rackham. Same basic rear structure, defined attachment points for motors and suspension arms, and a defined strategy for crash protection. From one architecture, many cars. The same sort of modularity is employed throughout the architecture, stem to stern, to ease development of interior components like dash, and readily change bodywork.

“The LEVA architecture can be configured to accommodate two different types of battery: an underfloor slab [a variation on the now-classic skateboard] and a mid-mounted ‘chest.’ The batteries are of differing capacities depending upon the required vehicle attributes and number of occupants. All batteries are combinations of a common module,” says Rackham. For 2-seat sports cars, the architecture offers two wheelbase lengths and also smaller and larger wells to hold the batteries directly behind the passenger cabin. With the larger battery, the rear structure will take twin electric motors. The third variant is for a longer wheelbase 2+2 GT car, with the batteries laid under the floor, with the option of a single or twin motor set-up.

“We assume 800 Volt or higher will be demanded during the lifetime of the platform,” says Rackham, this being the standard Germans and other Europeans are working to. “An 800 Volt charging infrastructure enables faster charging due to lower connector current. For the HV systems, the higher the better, with the limitation being available components.”

Unlike the $2 million Lotus Evija hypercar, which has a carbon-fiber structure, LEVA will rely on Lotus’s proven expertise in extruded and chemically bonded aluminum structures, pioneered in the highly innovative Lotus Elise more than two decades ago.

“LEVA is an extruded and bonded aluminium chassis. The rear subframe uses a high-strength high-ductility BD1 aluminium compound developed as part of the Project LEVA collaboration by Brunel University London,” says Rackham.

“The advantage at Lotus is that we are material- and process-independent. We are not tied to using a specific material or manufacturing process and will use what is best for the application. This is a huge advantage to our engineering consultancy client base and we will work with whatever process or material we are required. However, we pioneered the bonded and extruded chassis technology in automotive applications and therefore, there is no other manufacturer that knows more about this than Lotus. For the LEVA program, this technology and material is the best solution in terms of weight, strength, stiffness and efficiency,” says Rackham.

Lotus Managing Director Matt Windle stipulated that the battery of the sports car needed to match the weight of the existing supercharged 3.5-liter Toyota V6 used in the outgoing Evora and incoming Emira, an ambitious goal considering all the engineers and scientists in the world have yet to deliver the Holy Grail, a major efficiency breakthrough in battery chemistry and packaging dimensions.

“We have achieved that goal, but we are still pursuing weight optimization of the battery so have no definitive figures at this point. But it is not just the weight of the battery, but where it is positioned,” says Rackham, and herein lies the promise of an exceptional lightweight and agile electric sports car. Keep in mind that most electric cars weigh close to or more than 5000 pounds. If the battery and electric motor(s) weight is close to the same as an internal combustion engine, its gearbox and full fuel tank, Lotus will have a sports car perhaps comparable to super sports cars that weigh just over 3000 pounds. Or at least that is the hope.

“For a sports car and our EV hypercar, the Evija, the battery is mid-mounted, where the engine and gearbox would be in an internal combustion car. For the ‘chest’ battery behind the occupants the resultant vehicle center of gravity is further forward and lower than that of a conventional 3.5-liter V6. This gives the benefit of agility from the low polar moment of inertia and means that the driver and passenger will sit lower, a vital perception for a sports, super or hyper car. However, LEVA can take both chest batteries and slab [underfloor skateboard] batteries all of varying sizes for particular applications.”

With this positioning of the battery, weight distribution should be close to optimal, and the car should change directions with characteristic Lotus immediacy. According to Rackham, the mass and packaging of the battery, cabling and motor(s) approximates the weight and physical dimensions of a comparably powerful internal combustion powertrain. If this proves true, Lotus will have extraordinary electric sports cars.

It’s important to note that Lotus is not using a 2-speed gearbox in the Evija hypercar, which indicates that any future battery-electric Lotus sports cars will not have the added weight of a gearbox. But here Rackham will not provide definitive information, though in the video it’s hard to see where a 100-150+ pound gearbox might be packaged. Purist sports cars for the road deliver exquisite balance and a sense of immediacy at speeds below 120 mph. A gearbox likely will not be needed.

“Lotus Evija is single speed—we aren’t chasing 0-60 mph times with the Evija, although it is phenomenally quick over that sprint. But the rate of acceleration from 60 mph to 120 mph and from 120 mph to 180 mph doesn’t change—it reaches 180 mph in less than nine seconds with each 60-mph acceleration interval being less than three seconds.” Acceleration in Evija is unrelenting up to 180 mph. But how much engineering cascades from Evija to the LEVA? One is carbon-fiber, the other aluminum-intensive.

“First of all, we have been conducting advanced R&D into EVs and hybrids as part of the Lotus Engineering consultancy for many years,” says Rackham. Remember that the very first Tesla was essentially a Lotus Elise with a stretched wheelbase to accommodate the batteries. “However, specifically from the Evija, we have learned a lot in a number of areas of engineering and design, including the efficient management of air not just over and around the car, but also through the car. This leads to much greater aerodynamic downforce and efficiencies and is made possible by the differences between EV powertrains and internal combustion in terms of packaging.”

Proof is found in any examination of the rear fenders and rear panels of Evija, where one notices enormous and carefully contoured tunnels that start ahead of the rear wheels and exit above the rear diffuser. One might mistake these “venturis” for exuberant design, the guys with felt tip pens a little out of control. But the venturis offer aerodynamic advantage allowed by the compact physical dimensions of electric motors and the forward placement of the batteries. They are similar to venturis seen on the Ford GT, but are far larger, more aggressive, and package better than on the internal combustion Ford.

“We have also a much greater understanding of how power and torque in EVs are applied compared to an internal combustion car where maximum torque is at lower rpm. We have learned how these extreme performance figures [of electric vehicles with 100 percent of torque available at 0 rpm, instantly] can be managed and optimized for the best driving experience possible. We do stand ‘For The Drivers’ and it is extremely important that we continue to provide the best and most enjoyable driving experience in everything we do!” Managing torque delivery and also torque vectoring, meaning how much torque is applied across the axles to the individual wheels—left to right, to the inside and outside driven wheels during cornering—has been an engineering and scripting exploration among all electric vehicle makers. The ability to meter torque at both the motor itself instantly and accurately at each wheel under all cornering conditions can lead to tremendous gains in handling. Combine that with the proven method of applying millisecond touches of braking to individual wheels to prevent loss of traction and a car can achieve almost cat-like balance—how terribly Lotus.

Unlike the most recent European high-performance electric vehicles, Lotus does not intend to use motors on the front wheels, at least for now. “Front motors are being considered, but we have to protect the fundamental Lotus principles of light weight, agility and steering feel,” says Rackham, the same argument that applies to use of a 2-speed gearbox. This differentiates Lotus from Rimac, Pininfarina and the most aggressive all-wheel-drive Porsche Taycans. Clearly the goal is to retain purity of steering feel and keep vehicle weight as low as possible.

In LEVA, Lotus has also defined their battery strategy for their first-generation of electric vehicles.

“A common battery module is used throughout; the number of modules varies to suit the required performance. The ‘slab’ configuration is the smaller block laid flat,” says Rackham. This is shown in the animation, the battery laid out flat directly under the passenger cabin, a variation on the now-classic skateboard.

“LEVA will be able to accommodate alternative modules as battery technology develops. We won’t give away the weight distribution yet, but we can say that in recent years all our cars have been mid-engine and have around 40:60 front to rear and that is certainly the best solution,” says Rackham.

“Lotus is always about innovation, not just evolution. With our high-level backing from our shareholders, we now have the resources and expertise to lean on the globally influential and rapidly growing Geely,” says Rackham. “There is a huge enthusiasm and desire from the global market for Lotus to diversify beyond sports cars, and while the sports cars are vital to the business, we will have an expanded product range to include SUVs and sedans and these are already in development and the first of which will come out next year—2022. It is a very exciting period ahead, but this is now a reality which Lotus has been working towards over the last 73 years.”