Lotus took along its very new Evora 414E Hybrid to the 2010 Geneva Motor Show. A technology demonstrator, it was the first project sanctioned by Lotus Engineering’s Director Dr. Robert Hentschel after he joined the company in January.
“It is the result of four weeks’ work—which was tough on the project team!” said Hentschel, who was formerly COO, North America, of EDAG and is now responsible for Lotus Engineering worldwide, reporting to CEO Dany Bahar.
“The Evora 414E Hybrid is not a production car, but it is a technology platform for Lotus, integrating our core competences,” explained Hentschel. The Evora Hybrid project had been under consideration before his appointment at Lotus, but he gave the green light for the car to be at Geneva. It uses a plug-in hybrid system, incorporates an ICE (internal-combustion engine) range extender, and has two electric motors providing drive to each rear wheel independently. Use of a single-speed geartrain integrated into a common transmission housing facilitates torque vectoring.
Total output is 304 kW (408 hp), with the two electric motors each producing 152 kW and 400 N·m (295 lb·ft), providing performance figures that include a 0-97 km/h (0-60 mph) time of 4.0 s and a total hybrid range of 483 km (300 mi).
Packaging in a conventional sports car is often difficult, and the hybrid application brought challenges, but the Evora’s 2+2 seating capability and trunk size helped overcome them. A significant visual cue that the car is unique is an integrated glass roof and engine cover.
The range extender (announced last year) is a 1.2-L three-cylinder producing 35 kW (47 hp) at 3500 rpm via the integrated electrical generator. It has an aluminum monobloc integrating the cylinder block, cylinder head, and exhaust manifold in one casting. It is compact and has a mass of only 85 kg (187 lb). The generator both recharges the battery, a 17-kW·h lithium-polymer unit, and is used as a motor to start the range extender.
EVO Electric’s Axial Flux motor/generator technology is featured in the car. The powertrain concept is expected to have a lower overall CO2 footprint than a fully electric car of comparable performance and operating range due to the reduced battery capacity requirements, says EVO Electric.
Battery power provides a range of about 56 km (35 mi). A conventional domestic electric supply can be used to give an overnight battery recharge. The battery’s size has been determined by Lotus using vehicle simulation tools. This has obviated the use of a larger and more expensive battery that for many short journeys would be an unnecessary weight.
Operation of the range extender, the power management of the batteries, and motor control are looked after by Lotus’ electronic control units and software systems.
Hentschel underlines the importance of the Hybrid concept: “It is sometimes difficult to demonstrate engineering capability to a customer, so we have built the Evora 414, which combines the capabilities that we can bring to niche vehicles.”
The use of two electric motors with the ability to generate different torque levels for each rear wheel reduces the conflict between stability and response, bringing what Lotus describes as a markedly higher level of vehicle dynamics control. The system produces a turning moment at the rear of the vehicle in addition to the steering input, providing enhanced straightline stability.
The system incorporates lateral sensors to provide stability control characteristics and steering response usually associated with heavy and expensive rear-steer systems, stated Lotus at Geneva.
To give the Evora Hybrid an added sports car feel, a paddle shift is fitted, which simulates a seven-speed gearbox, although the car has only a single-speed unit. “This provides an interruption of torque—necessary for our customers,” stated Hentschel. “It is a function of a niche vehicle of this type and can be simply switched off if not required.”
The car also has a HALOsonic sound synthesis system developed in association with Harman International. It provides cabin sound and an external warning of the approach of the vehicle. Simulated in-cabin engine noise was demonstrated by Lotus in the mid-1980s, but Hentschel believes it now has great market potential: “We have to find the right time for these things.”
The use of alternative materials has long been a Lotus strength, and at Geneva it also showed the Evora Carbon Concept. The interior features exposed carbon fiber and Alcantara trim. The carbon fiber roof is structural and the material is used for a rear diffuser and front splitter. Design Director Donato Coco said that the use of high-tech materials offered a synergy with the company’s image.
The Proton Concept city car, which uses a Lotus Engineering hybrid powertrain, including the 1.2-L range extender, was also shown at Geneva. It was unveiled on the stand of Italdesign, responsible for its styling.