/ Guinness World Records · 2018 & 2019
The most efficient
Eta is over 175 times more efficient than a Tesla Model 3.
*Gasoline energy converted to kWh equivalent. Bars not to scale below 1%; the record cars would make the others invisible.
Named for the Greek letter engineers use to denote efficiency, Eta was designed with a singular goal: to hold the title of "World's Most Efficient Electric Vehicle."
The vehicle features significantly improved aerodynamics compared to Maxwell, a highly-efficient direct drive motor, a tracking step-down converter to minimize motor controller switching losses, and a numerically optimized driver strategy.
On record day, driving at an average of 15.0 mph with a 50 kg driver, the same conditions as the Shell Eco-marathon, Eta posted 797 mi/kWh, breaking TU Munich's record of 765.
At 27,482 MPGe, Eta could drive around the world on less than a gallon of gasoline equivalent.
| Official result | 797 mi/kWh · 1,283 km/kWh · 27,482 MPGe |
| Race-ready weight | 20 kg |
| Chassis | Carbon fiber monocoque, Nomex honeycomb |
| Powertrain | Direct-drive Mitsuba M00512-IV |
| Electronics | Custom sensorless controller + tracking buck converter |
| Measured CdA | 0.0328 m² |
| Power at 15 mph | 18.8 W, less than a laptop charger |
On July 21, 2018, our hydrogen-powered Maxwell broke the PAC-Car II's long-standing world record for fuel efficiency, setting the new bar at 14,573 MPG, enough to circumnavigate the globe on the energy in a single gallon of gasoline.
Maxwell uses a dead-end anode fuel cell with passive humidification, which allows for simple operation.
Every loss in the vehicle, from aerodynamic drag to bearing drag to tire rolling resistance, was individually quantified to build a unified model of the car's performance.
| Official result | 14,573 MPG · 6,196 km/l |
| Race-ready weight | 26 kg |
| Fuel cell | Horizon 100 W with custom controller, 58.4% efficiency |
| Hydrogen storage | Horizon metal-hydride |
| Load leveling | 19 V / 170 F supercapacitors |
| Motor | Koford 60LH175A, custom auto-throttle |
From a heavy first build with an in-hub brush motor to aluminum frames, custom bodies, and our first custom motor controller.
Maxwell wins Battery-Electric Prototype at 296 mi/kWh with a carbon fiber monocoque and custom electronics.
Maxwell repeats first place (368 mi/kWh), our backup car Gemini wins the hydrogen prototype class, and on July 21, hydrogen-powered Maxwell sets the Guinness World Record for fuel efficiency: 14,573 MPG.
Eta sets the Guinness World Record for the most efficient electric vehicle: 797 mi/kWh, a record that still stands.
We take everything we learned building record-setting prototypes and apply it to a street-realistic Urban Concept car. See where it's headed →