Ford's prototype operation occupied a shop built in the 1950s for lower-volume Lincoln Continentals. Decades later, an unfinished, top-secret Bronco might be hidden inside. Taking out a phone near the build could bring serious trouble. The rules were strict because every vehicle in the shop contained parts, decisions, and problems that had not yet reached a production line.
John Gravelyn moved from Ford's established operation to Rivian's prototype environment, where teams needed custom parts immediately and had fewer test vehicles available to reveal mistakes. His move made one thing clear: building an EV quickly is not simply a software job. Someone still has to bring the unfinished hardware, sensors, test requirements, supplier parts, technicians, and engineering teams together in a working vehicle.
Building an EV quickly is not simply a software job.
Inside Ford, one prototype had to unite every engineering team
Gravelyn joined Ford as a prototype planner and soon became a prototype build engineer. He did not own a single component. His job was to get specialists and program teams to deliver one complete prototype on time. One engineer might focus on a headlight while another worked to reduce weight. Both could do their jobs correctly and still create trouble where their work intersected. The prototype build engineer had to catch those conflicts before the vehicle moved forward.
The number of builds varied by program. A limited change, such as new F-150 headlights or a vehicle intended for another market, might require 30 prototypes. Starting an entire Bronco line could involve a couple of hundred vehicles. The scale differed, but the purpose was the same: find failures while teams could still change the parts and processes. Gravelyn found that programs with more trouble in the prototype shop usually brought more trouble to the production line, including recalls. A poor fit or unresolved build issue does not improve when production begins.
A poor fit or unresolved build issue does not improve when production begins.
His nine months in Ford's emissions lab showed how testing duties were changing. He arrived about a week before COVID sent employees home, making it an unusual assignment, but the Mustang Mach-E work was instructive. A facility associated with emissions testing was also used for electrical range testing. The equipment and testing discipline remained useful even as the measurement changed. The work still required controlled conditions, repeatable procedures, and people who could distinguish a genuine vehicle problem from a flawed test.
At Rivian, custom parts replaced Ford's carryover playbook
Ford could draw on an existing portfolio. Even during a major engineering change, teams could carry over some hardware, systems, or proven details. Components could also move between vehicle programs. Carryover does not eliminate prototype work, but it provides known parts and established suppliers. Rivian had far less of that foundation. Gravelyn sourced parts the company could not make in-house.
He had to build supplier relationships that could deliver custom parts on compressed timelines. The work was physical and repetitive: make the component, install it, inspect the result, and try again. A part might fit the available space but lack sufficient strength. Another might solve one packaging problem while creating a different one nearby. Rivian tested fewer prototype vehicles than Ford, so every build had to produce useful answers quickly. A marginal part had fewer places to hide.
A marginal part had fewer places to hide.
Speed helped Rivian become the first electric truck to reach the market, but the mechanical work remained difficult. On a MotorTrend transcontinental trail test, Rivian vehicles pulled out the Ram support truck most of the time. That result came from a complete vehicle, not software alone. As the workforce grew from 3,000 to over 15,000 employees, Rivian began to resemble Ford in its need to operate as a mature company. Gravelyn found that later stage less fun, but a larger manufacturer cannot treat every build as an improvised prototype.
Why technicians remain central to EV work
A software designed vehicle can gain functions through an over-the-air update. Lights can operate differently, efficiency can improve, and additional range can become available without replacing a physical assembly. That works once the vehicle and software are stable. Prototype development is messier. Sensors, custom parts, control logic, and unfinished software must all work together. When something fails, it may not be obvious whether the fault began in the hardware, software, installation, or calibration.
Automating vehicle manufacturing does not eliminate end-of-line work. Finished vehicles still require updates, troubleshooting, diagnostics, and repair. Gravelyn called technicians his secret weapon as an engineer because they often knew more about practical vehicle failures than engineers did. On the shop floor, that is easy to understand. A technician who repeatedly sees the same connector seated incorrectly, the same update fail, or the same symptom appear under load develops knowledge that cannot come from reading a single engineering requirement.
Gravelyn called technicians his secret weapon as an engineer because they often knew more about practical vehicle failures than engineers did.
Preparation does not mean memorizing every possible fault code or repair. Modern vehicles contain too many interacting systems for that. Technicians need a repeatable troubleshooting process: define the symptom, ask precise questions, separate facts from assumptions, test one likely cause, and see whether the result changes. AI can help interpret information and refine the next question, but it cannot replace verification on the vehicle. Four years spent learning diagnostics, controls, and disciplined problem solving can also lead beyond one type of car. Powertrains will change, but manufacturers will still need capable problem solvers at the end of the line.
