The Chevrolet Volt: A Revolution in Automotive Engineering

Introduction

The Chevrolet Volt, a trailblazing electric vehicle, made its debut at the 2007 North American International Auto Show as a concept car. The Volt was a significant departure from the General Motors (GM) EV1 of the 1990s, boasting four doors, rear liftgate, seating for four passengers, and a top speed of 100 miles per hour (160 km/h). The Volt’s development was driven by GM’s ambition to create a “Prius fighter” that would revolutionize the electric vehicle market, drawing inspiration from the Tesla Roadster and the rapid advancement of lithium-ion battery technology.

The Birth of the Chevrolet Volt Concept Car

The Volt’s conception can be traced back to GM’s then-Vice Chairman for global product development, Robert Lutz, who was seeking a leapfrog product akin to Apple’s iPod. Lutz was particularly inspired by the Tesla Roadster, an all-electric sports car that debuted in 2008. Despite internal opposition stemming from the EV1 electric vehicle program’s billion-dollar losses in the 1990s, Lutz pushed for the development of the Volt after the 2006 Detroit Auto Show.

Jon Lauckner, GM Vice President for global program management, suggested the use of a smaller battery pack with a small combustion engine driving a generator to extend the range without a mechanical connection between the gasoline engine and the drive wheels. This approach aimed to circumvent the expensive battery, range anxiety concerns, and the lack of public charging infrastructure that plagued previous electric vehicle programs.

The Volt’s Design Parameters and Goals

The Volt’s initial design parameters, which included a 40-mile (64 km) all-electric range, were primarily aimed at reducing battery size and costs. This target range was chosen based on research indicating that 78% of daily commuters in the U.S. travel 40 miles or less. This range would allow most drivers to rely on electric power for their daily commutes, assuming overnight charging at home.

To achieve this range, the Volt required a lithium-ion battery pack with an energy storage capacity of 16 kWh. The battery’s state of charge (SoC) was limited to 30% to maintain operational performance under various conditions and minimize degradation, ensuring at least a ten-year lifespan. The Volt was designed to accommodate four or five passengers and have a gasoline engine/generator range of 250 to 300 miles (400 to 480 km).

E-Flex (Voltec) Drive System

The Volt was the first vehicle to utilize the E-Flex (later renamed Voltec) drive system, a new family of common powertrain components for electric propulsion. This powertrain aimed to standardize components for future electric vehicles and allow for multiple, interchangeable electricity-generating systems. The E-Flex system could adapt vehicles to pure battery electric, fuel cell-powered, or other energy sources, such as gasoline, diesel, biodiesel, ethanol fuel (E100), or flex-fuel (E85). Regenerative braking would also contribute to on-board electricity generation.

The Volt’s Powertrain and Advanced Materials

The Volt concept car featured an electric motor, a 16 kWh (58 MJ) lithium-ion battery pack with 136 kW of peak power, and a genset consisting of a 1.0 L, 3-cylinder turbocharged flex-fuel capable engine linked to a 53 kW (71 hp) generator. This genset was called an electric vehicle (EV) range extender, and the vehicle was propelled by an electric motor with a peak output of 120 kW (160 hp), delivering 236 lb⋅ft (320 N⋅m) of motoring torque.

To reduce the Volt’s weight, GM used advanced materials from GE Automotive Plastics, which helped decrease the vehicle weight by up to 50 percent.

Fuel Efficiency and Total Driving Range

The Volt concept featured a 12 US gal (45 L; 10.0 imp gal) fuel capacity, providing the vehicle a total driving range of around 640 mi (1,030 km), considering a gasoline fuel efficiency of about 50 mpg‑US (4.7 L/100 km; 60 mpg‑imp) and a 40 mi (64 km) all-electric range. GM estimated that for daily drives of 60 mi (97 km) combined with an overnight recharge, the Volt would achieve an effective gasoline fuel economy of 150 mpg‑US (1.6 L/100 km; 180 mpg‑imp).

GM also highlighted the Volt’s potential to reduce dependence on imported oil if E85 ethanol was used instead of gasoline to power the on-board generator engine. Robert Lutz noted that using E85 would result in a fuel economy figure of 525 miles per (equivalent) petroleum gallon since only 15% of gasoline is used in this blend.

Battery Development Challenges and Pricing

At the time of the Volt concept’s unveiling, the required rechargeable batteries needed to make the Volt a viable vehicle were not yet available on the market and had to be developed. The concept car was powered by two 12-volt conventional car batteries, providing enough power for the vehicle to move at low speeds in the stand.

Lutz initially stated that the Volt was expected to sell for around $30,000, based on the cost of a conventional car of that size with a conventional four-cylinder engine plus an additional $8,000 for the lithium battery. However, as developers realized that the Volt could not share components from GM’s compact car platform and considered the cost of a compact 110 kW (150 hp) electric motor and specialized microprocessors to control energy flow, the Volt’s base price was eventually set at around $40,000. The $1 billion cost to develop the Volt was equivalent to creating three vehicles on an existing platform.

Conclusion

The Chevrolet Volt was a groundbreaking concept car that showcased the potential for electric vehicles in the automotive market. With its innovative design and advanced technology, the Volt set the stage for a new era of electric vehicles that could compete with traditional gasoline-powered cars. Despite challenges in battery development and pricing, the Volt paved the way for a more sustainable future in transportation and signaled a significant shift in the automotive industry’s approach to electric vehicles.