Ford released battery-health data from more than 36,000 2021-model-year Mustang Mach-Es driven across the United States and Canada. The fleet accumulated approximately two billion cumulative all-electric miles.
After an average of 5.2 years and 55,000 miles, the fleet retained 92% of its original battery health, according to Ford. Ford’s data also shows that 95% of vehicles fell between 87% and 97% battery health, with results clustering well above the low end.
High-mileage performance held up similarly well. More than 2,000 Mach-Es past 100,000 miles averaged better than 91% battery health, roughly one percentage point below the broader fleet average.
Ford also tracked more than 30 vehicles that had exceeded 200,000 miles. Those averaged 88% battery health.
For a practical reference point, a 2021 Mach-E originally rated for 305 miles of EPA range would theoretically deliver roughly 280 miles at 92% retained capacity. Temperature, speed, terrain, and driving style will all affect that figure in either direction.
What Ford’s Study Does, and Doesn’t, Prove
The dataset is large and informative, but it reflects fleet averages from Ford’s own battery-health data rather than a controlled independent study.
Ford’s analysis covers real-world use across tens of thousands of vehicles, with charging patterns, climate exposure, and driving histories that were not evenly distributed. These are averages, not performance guarantees for any individual Mach-E.
The data also applies specifically to 2021 Mach-Es. Extending the findings to other Ford EVs or different battery chemistries requires separate evidence.
Outside Data Points in the Same Direction
Third-party findings broadly align with Ford’s numbers, though direct comparisons require caution because the methodologies differ.
Aviloo’s analysis of 500,000 EV battery tests found most models retained between 90% and 94% health around 93,000 miles. The Mach-E registered roughly 92.5% in that dataset, according to InsideEVs.
Recurrent, which tracks observed range rather than raw capacity, reported 95% range retention at five years for EVs in its dataset. Its methodology is not directly comparable to Ford’s battery-health analysis.
Battery-health tests, observed range figures, and state-of-health estimates measure related but distinct things. The directional agreement across sources is encouraging, but it should not be treated as definitive confirmation.
Habits That Slow the Decline
Ford’s maintenance guidance focuses on temperature management and charging behavior as the primary factors owners can control.
Avoiding sustained exposure to extreme heat is a priority. Parking in shade during hot weather and using cabin preconditioning while the vehicle remains plugged in can help reduce thermal stress on the battery.
For daily charging, Ford recommends Level 2 over DC fast charging, which is better reserved for road trips and occasional use. Keeping the battery within a moderate charge range, commonly cited as roughly 20% to 80%, reduces wear over time, though Ford’s specific guidance varies by battery configuration.
One Thing Fleet Averages Cannot Tell You
A strong fleet result is not a substitute for a vehicle-specific check when buying used.
Before purchasing a used Mach-E, prospective buyers should request a battery diagnostic specific to that vehicle. A fleet average cannot determine whether a particular example experienced extreme heat, repeated fast charging, or prolonged storage at a high state of charge.
