Lotus Engineering adds lightness to a Crossover Utility Vehicle

California Air Resources Board (CARB) publishes results of Lotus Engineering’s vehicle mass reduction study on a Crossover Utility Vehicle (CUV)

  • Results show a total vehicle mass reduction of 31% (528.3 kg or 1,162 lbs.) and a $239 (£150 / €188) saving in overall vehicle cost.
  • Body structure utilises advanced materials including high-strength steels, aluminium, magnesium and composites along with high tech joining and bonding techniques.

Following on from Lotus’ successful “Phase One” study, published in 2010, which looked at the empirical and theoretical weight saving for a standard CUV, Lotus Engineering conducted further research to confirm if a lightweight and commercially feasible body structure has the potential to meet or exceed the requirements for size, luggage volume, comfort, crashworthiness and structural integrity.

Lotus Engineering’s “Phase Two” body structure design was based on the dimensions of a 2009 Toyota Venza CUV and utilised advanced materials such as high-strength steels, aluminium, magnesium and composites along with advanced joining and bonding techniques to achieve a substantial body and overall vehicle mass reduction without degrading size, practicality or performance. The body mass was reduced by 37% (311 lbs. or 141.6 kg), which contributed to a total vehicle mass reduction of 31% (1,162 lbs. or 528.3 kg) including the mass savings of other vehicle systems (interior, suspension, chassis, closures, etc.) that had previously been identified in “Phase One”.

The detailed Computer Aided Engineering (CAE) analysis undertaken indicated that a 31% mass-reduced vehicle with a 37% lighter Body-in-White (BIW) structure has the potential to meet U.S. Federal impact requirements. This includes side impact and door beam intrusion, seatbelt loading, child seat tether loadings, front and rear chassis frame load buckling stability, full frontal crash stiffness and body compatibility and frame performance under low-speed bumper impact loads as defined by the Insurance Institute for Highway Safety (IIHS). The result is a BIW design with a 20% increase in torsional stiffness over the class leading CUV.

Although the significant mass savings in the BIW design results in an increased BIW cost of $723 (£456 / €568), the overall vehicle cost is reduced through savings of $239 (£150 / €188) identified across the whole vehicle and when manufacturing and assembly costs are included in the analysis. A significant reduction in the parts count from 269 to 169, achieved by an increased level of component integration, also helped offset the increased BIW piece cost.

The background to the study

In April 2010, Lotus Engineering concluded the first phase of a study which substantiated that a reduction in vehicle mass could be achieved for medium production volume vehicles (approximately 50,000 units per year) with a 23% reduction in fuel consumption. In September 2010 the California Air Resources Board (CARB) commissioned Lotus Engineering to initiate Phase Two of the study and take a deeper look into the future of lighter, more efficient vehicles manufactured using lighter yet stronger materials.

Lotus has always been about Lightweight

When Lotus founder Colin Chapman coined the phrase “performance through light weight” he was referring to much more than mere accelerative performance. In the broader sense he meant that a lighter vehicle does everything better, including being more fuel efficient. Over the past 60-plus years, Lotus road and racing vehicles have consistently benefited from this core philosophy and Lotus has developed a strong reputation as a leader in lightweight vehicle technologies.

After decades of most manufacturers building increasingly heavy, feature-laden cars, now the very aggressive corporate average fuel economy (CAFÉ) standards increasing from a target of 35.5 mpg in 2016 to 54.5 in 2025 have all manufacturers reevaluating the virtues of mass reduction and prioritising the materials, technologies and production methods that will enable lighter, stronger and more efficient vehicles.

Lotus to cease production of 2ZZ-GE engined Elise/Exige

Lotus Cars has notified US dealers that the current generation of 2ZZ-GE engined Exige and Elise will cease production this July on Model Year 11. Toyota has already stopped production of the 2ZZ-GE engine and Lotus has been buliding cars using stockpiled engines ever since.

There are to be 3 final Elise and Exige versions – “Final Editions” to be built between now and July 2011, for arrival in the US and Canada between June – August 2011. These are to be produced in strictly limited numbers as the supply of engines for production is approaching exhaustion. Interested customers need to reserve their cars NOW. The specifications of the 3 final edition cars are listed below:

Exige S260 Final Edition

Production Run: 30
An excellent value proposition, available in choice of color, these are based on the current Exige 240 spec with power enhanced to 260bhp. Tour pack, track pack and LSD are standard equipment.

Basics
• 257 horsepower supercharged and intercooled 1.8 Liter, mid-mounted 4-cylinder engine
• Multi-point fuel injection system with electronic ignition and throttle control
• Synchromesh 6-speed transaxle with lockout reverse gear
• Variable slip traction control
• Launch Control

Standard Fitment
• Touring Package with sport seats trimmed in your choice of black, red, magnolia or biscuit
leather.
• Track Package with double adjustable Ohlins dampers.
• Torsen (Torque-sensing) Limited Slip Differential.
• Black Y type 5 spoke forged wheels with A048 tires.
• Metallic paint range at no additional charge.

Options
• Choice of full range of current colors
• StarShield

Production Details
• Limited to 30 units for North America
• May/June production

MSRP
• $67,500 plus destination

Exige S260 Final Edition – Matte Black

Production run: 25
Based on the stunning Matt Black Exige Scura sold in Europe with great success, some changes for the US market to ensure that this car is even better value.

Basics
• 257 horsepower supercharged and intercooled 1.8 Liter, mid-mounted 4-cylinder engine
• Multi-point fuel injection system with electronic ignition and throttle control
• Synchromesh 6-speed transaxle with lockout reverse gear
• Variable slip traction control
• Launch Control

Standard Fitment
• Touring Package with sport seats trimmed in black Alcantara
• Track Package with double adjustable Ohlins dampers
• Torsen (Torque-sensing) Limited Slip Differential
• Black 5-spoke ultra lightweight forged wheels with A048 tires
• Special Matte Black paint
• Special numbered plaque

Options
• No options available

Production Details
• Limited to 25 units for North America
• May/June production

MSRP
• $69,900 plus destination

Elise SC Final Edition

Production run: 15
With a color scheme based upon the “Club Racer” Elise sold in Europe. Available in four colors with a high standard specification makes this Final Edition Elise an excellent value proposition. Extremely limited production run of 15 cars to close out the model in North America.

Basics
• 220 horsepower supercharged 1.8 Liter, mid-mounted 4-cylinder engine
• Multi-point fuel injection system with electronic ignition and throttle control
• Synchromesh 6-speed transaxle with lockout reverse gear

Standard Fitment
• Touring Package with sport seats trimmed in black Alcantara
• Bilstein sport pack dampers with Eibach springs
• Torsen (Torque-sensing) Limited Slip Differential
• Black 5 Y- spoke forged wheels with A048 tires
• Black rear diffuser
• Matte Black painted hard top, roll bar cover, transom panel and door mirrors
• Special numbered plaque

Options
• 4 no charge color options: Ardent Red, Aspen White, Chrome Orange and Carbon Grey
• StarShield

Production Details
• Limited to 15 units for North America
• May/June production

MSRP
• $57,500 plus destination
• $995 StarShield

Information via Lotus of Atlanta and Lotus of Newport Beach

Last 2ZZ-GE powered Elise Delivered

Lotus commemorated their successful relationship with Toyota today (17th September) at a celebration at the British Embassy in Tokyo where Lotus CEO Dany Bahar presented Toyota Motor Corporation President Akio Toyoda with a specially equipped Lotus Elise powered by the last ever Toyota 2ZZ-GE VVTL-i engine. The occasion marked the end of an era and the start of an even stronger relationship between the two companies.

Dany Bahar, CEO of Group Lotus (left) presented  the keys to the Lotus Elise R alongside a commemorative plaque encased in a leather wallet to Toyota Motor Corporation President, Akio Toyoda (right)
Dany Bahar, CEO of Group Lotus (left) presented the keys to the Lotus Elise R alongside a commemorative plaque encased in a leather wallet to Toyota Motor Corporation President, Akio Toyoda (right)

As part of the celebration, Lotus CEO Dany Bahar said: “The presentation of Toyota’s last 2ZZ engine in the Elise is a symbolic gesture of our continued respect and deep appreciation for our partner not only acknowledging our past but also looking forward to our future together.”

  David Warren, British Ambassador to Japan (left), Dany Bahar, CEO of Group Lotus (centre) and Toyota Motor Corporation President, Akio Toyoda (right) with the Lotus Elise R
David Warren, British Ambassador to Japan (left), Dany Bahar, CEO of Group Lotus (centre) and Toyota Motor Corporation President, Akio Toyoda (right) with the Lotus Elise R

Toyota Motor Corporation President responded: “A Toyota engine in a Lotus car creates a completely unique drive feeling – a special blend featuring the best of Lotus and Toyota that we hope many car lovers continue to experience and enjoy.”

Dany Bahar, CEO of Group Lotus (right) and Toyota Motor Corporation President, Akio Toyoda (left) in the Lotus Elise R housing the final Toyota 2ZZ-GE engine produced
Dany Bahar, CEO of Group Lotus (right) and Toyota Motor Corporation President, Akio Toyoda (left) in the Lotus Elise R housing the final Toyota 2ZZ-GE engine produced

Based on the successful cooperation with Toyota so far, Lotus has decided to take the relationship with Toyota to a new level that will enable Lotus to create tailor-made powertrain solutions for future Lotus cars.

For more details on exactly how Lotus will be partnering with Toyota in the future, simply look to the Lotus global unveiling at the Paris Motor Show on September 30th where Lotus will showcase their new line up to the world’s media. The eagerly anticipated event marks the dawn of a new era for Lotus and will highlight exactly why both companies are so proud of their relationship.

Lotus Lightens a Toyota Venza

2020 Toyota Venza

Lotus Engineering has conducted a study to develop a commercially viable mass reduction strategy for mainstream passenger vehicles. This study, released by the International Council on Clean Transportation, focused on the use of lightweight materials and efficient design and demonstrated substantial mass savings. When compared with a benchmark Toyota Venza crossover utility vehicle, a 38% reduction in vehicle mass, excluding powertrain, can be achieved for only a 3% increase in component costs using engineering techniques and technologies viable for mainstream production programmes by 2020. The 2020 vehicle architecture utilises a mix of stronger and lighter weight materials, a high degree of component integration and advanced joining and assembly methodologies.

Based on U.S. Department of Energy estimates, a total vehicle mass reduction of 33% including powertrain, as demonstrated on the 2020 passenger car model, results in a 23% reduction in fuel consumption. This study highlights how automotive manufacturers can adopt the Lotus philosophy of performance through light weight.

Dr Robert Hentschel, Director of Lotus Engineering said: “Lighter vehicles are cleaner and more efficient. That philosophy has always been core to Lotus’ approach to vehicle engineering and is now more relevant than ever. Lightweight Architectures and Efficient Performance are just two of our core competencies and we are delighted to have completed this study with input from the National Highway Traffic Safety Administration and the U.S. Environmental Protection Agency to provide direction for future CO2 reductions. We believe that this approach will be commonplace in the industry for the future design of vehicles.”

The study investigated scenarios for two distinct vehicle architectures appropriate for production in 2017 and 2020. The near-term scenario is based on applying industry leading mass reducing technologies, improved materials and component integration and would be assembled using existing facilities. The mass reduction for this nearer term vehicle, excluding powertrain, is 21% with an estimated cost saving of 2%.

A benchmark Toyota Venza was disassembled, analysed and weighed to develop a bill of materials and understand component masses. In developing the two low mass concepts, Lotus Engineering employed a total vehicle mass reduction strategy utilising efficient design, component integration, materials selection, manufacturing and assembly. All key interior and exterior dimensions and volumes were retained for both models and the vehicles were packaged to accommodate key safety and structural dimensional and quality targets. The new vehicles retain the vision, sight line, comfort and occupant package of the benchmarked Toyota Venza.

Darren Somerset, Chief Executive Officer of Lotus Engineering Incorporated, Lotus’ North American engineering division which led the study, said “A highly efficient total vehicle system level architecture was achieved by developing well integrated sub-systems and components, innovative use of materials and process and the application of advanced analytical techniques. Lotus Engineering is at the forefront of the automotive industry’s drive for the reduction in CO2 and other greenhouse gas emissions and this study showcases Lotus Engineering’s expertise and outlines a clear roadmap to cost effective mass efficient vehicle technologies.”

Mass and Cost Summary

Base Toyota Venza

excluding powertrain

Lotus Engineering Design

System

Weight

(kg)

2020 Venza

2017 Venza

% Mass Reduction

% Cost Factor

% Mass Reduction

% Cost Factor

Body

383

42%

135%

15%

98%

Closures/Fenders

143

41%

76%

25%

102%

Bumpers

18.0

11%

103%

11%

103%

Thermal

9.25

0%

100%

0%

100%

Electrical

23.6

36%

96%

29%

95%

Interior

252

39%

96%

27%

97%

Lighting

9.90

0%

100%

0%

100%

Suspension/Chassis

379

43%

95%

26%

100%

Glazing

43.7

0%

100%

0%

100%

Misc.

30.1

24%

99%

24%

99%

Totals

1290

38%

103%

21%

98%

The 2020 Passenger Car Technical Details

Body

The body includes the floor and underbody, dash panel assembly, front structure, body sides and roof assembly. The baseline Toyota Venza body-in-white contained over 400 parts and the revised 2020 model reduced that part count to 211. The body-in-white materials used in the baseline Venza were 100% steel, while the 2020 model used 37% aluminium, 30% magnesium, 21% composites and 7% high strength steel. This reduces the structure mass by 42% from 382 kg to 221 kg.

The low mass 2020 body-in-white would be constructed using a low energy joining process proven on high speed trains; this process is already used on some low volume automotive applications. This low energy, low heat friction stir welding process would be used in combination with adhesive bonding, a technique already proven on Lotus production sports cars. In this instance, the robotically controlled welding and adhesive bonding process would be combined with programmable robotic fixturing, a versatile process which can be used to construct small and large vehicles using the same equipment.

Closures/Fenders

The closures include all hinged exterior elements, for example, the front and rear doors and the rear liftgate. One alternative approach included fixing the primary boot section to improve the structure, reduce masses and limit exposure to high voltage systems. A lightweight access door was provided for checking and replacing fluids.

The closures on the baseline Toyota Venza were made up of 100% steel. The low mass Venza closures/fenders would be made up of 33% magnesium, 21% plastic, 18% steel, 6% aluminium with the other 22% consisting of multiple materials. The mass savings are 41%, a reduction from 143 kg to 84 kg.

Interior

The interior systems consist of the instrument panel, seats, soft and hard trim, carpeting, climate control hardware, audio, navigation and communication electronics, vehicle control elements and restraint systems. There is a high level of component integration and electronic interfaces replace mechanical controls on the low mass model. For the 2020 model the instrument panel is eliminated replaced by driver and passenger side modules containing all key functional and safety hardware. A low mass trim panel made from a high quality aerated plastic closes out the two modules. The air conditioning module is incorporated into the console eliminating the need for close out trim panels; heated and cooled cupholders are integrated into the HVA/C module. The audio/HVA/C/Navigation touch screen contains the shifter and parking brake functions and interfaces with small electric solenoids. This eliminates conventional steel parking brake and shifter controls and cables as well as freeing up interior space.

The front seats mount to the structural sill and tunnel structure eliminating conventional seat mounting brackets (10 kg) and the need to locally reinforce the floorpan. The composite front seat structure utilises proven foam technology; the seat mass is reduced by up to 50%. The rear seat support structure is moulded into the composite floorpan eliminating the need for a separate steel support structure. The front and rear seats use a knit to shape fabric that eliminates material scrap and offers customers the opportunity to order their favourite patterns for their new vehicle. Four removable carpet modules replace the traditional full floor carpeting; this reduces mass and allows cost effective upgrading of the carpet quality. The floorpan is grained in all visible areas. The 2017 production interior mass was reduced from 250 kg to 182 kg with projected cost savings of 3%. The 2020 production interior mass was 153 kg with projected cost savings of 4%.

Chassis/Suspension

The chassis and suspension system was composed of suspension support cradles, control links, springs, shock absorbers, bushings, stabilizer bars and links, steering knuckles, brakes, steering gearbox, bearings, hydraulic systems, wheels, tires, jack and steering column.

The chassis and suspension components were downsized based on the revised vehicle curb weight, maintaining the baseline carrying capacity and incorporating the mass of the hybrid drive system.

The total vehicle curb weight reduction for the 2020 vehicle was 38%, excluding the powertrain. Based on the gross vehicle weight, which includes retaining the baseline cargo capacity of 549 kg and utilising a hybrid powertrain, the chassis and the suspension components were reduced in mass by 43%, with projected cost savings of 5%.

Front and Rear Bumpers

The materials used on the front and rear bumpers were very similar to the existing model to maintain the current level of performance. One change was to replace the front steel beam with an aluminium beam which reduced mass by 11%. The use of a magnesium beam was analysed but at the current time exceeded the allowable price factor.

Heating, Ventilation and Air Conditioning

The air conditioning system was integrated into a passenger compartment system and an engine compartment system. This section addressed the under hood components which included the compressor, condenser and related plumbing. The under hood components were investigated for technologies and mass.

The study showed a relatively small mass difference for the underhood air conditioning components based on both vehicle mass and interior volume. Because of the highly evolved nature of these components, the requirements for equivalent air conditioning performance and the lack of a clear consensus for a future automotive refrigerant, the mass and cost of the Toyota Venza compressor, condenser and associated plumbing were left unchanged for both the 2017 and 2020 models.

Glazing

The glazing of the baseline vehicle was classified into two groups: fixed and moving. The fixed glass is bonded into position using industry standard adhesives and was classified into two sub groups: wiped and non wiped.

Factors involved in making decisions about glazing materials include the level of abrasion it is likely to see during the vehicle life, the legislative requirements for light transmissibility, the legislative requirements for passenger retention and the contribution it will make to interior noise abatement.

The specific gravity of glass is 2.6 and the thickness of a windshield is usually between 4.5 mm and 5 mm, therefore the mass per square metre of 5 mm glass is approximately 13 kgs. The high mass of glass provides a strong incentive to reduce the glazed area of the body, reduce the thickness of the glass and find a suitable substitute that is lighter. Fixed glass on the side of the vehicle offers the best opportunity for mass reduction.

The mass of the baseline glazing was retained for both the 2017 and 2020 models; this was a conservative approach. It is possible that coated polycarbonate materials may become mainstream in the 2017 – 2020 timeframe for fixed applications.

Electrical/Lighting

The estimated mass savings for using thinwall cladding and copper clad aluminium wiring, as used on the 2017 model was 36% versus the baseline model. The lighting technologies section reviewed included diodes, xenon and halogen. The study also reviewed a variety of wireless technologies under development for non-transportation applications that could be used in this time period pending successful development for mobile applications.

More information
The full report, entitled ‘An Assessment of Mass Reduction Opportunities for a 2017 – 2020 Model Year Vehicle Program’ can be found at this link (pdf).

[press release from Lotus Engineering]