If you’ve ever wondered “how far can I go on a charge?” the honest answer involves understanding efficiency — kWh per mile or kWh per km. Battery size tells you how much energy you have; efficiency tells you how far that energy will take you.
This article explains how EV efficiency is measured, what numbers are normal, and what affects how efficiently you actually drive.
The basic math
Range = Battery capacity (kWh) ÷ Efficiency (kWh/mile)
If the difference between capacity and power is still fuzzy, the kW vs kWh breakdown is worth a quick read first.
A car with 70 kWh battery using 0.30 kWh/mile has 70 / 0.30 = 233 miles of range.
The same car using 0.40 kWh/mile in cold weather has 70 / 0.40 = 175 miles of range. 25% less range despite the same battery.
Efficiency, not battery size, is what determines your actual range under your actual conditions.
flowchart LR
A[Battery capacity<br/>kWh] --> C[Range<br/>miles]
B[Efficiency<br/>kWh per mile] --> C
D[Speed] --> B
E[Temperature] --> B
F[Driving style] --> B
style C fill:#2563eb,stroke:#1e40af,color:#fffUnits across regions
A note on units before we go further.
kWh per mile — common in North America. Miles per kWh — the inverse; same data, different orientation. kWh per km — common outside North America. Multiply by 1.609 to convert from per-mile. Wh per km — same as kWh/km divided by 1000. Easier to read for some. MPGe — Miles Per Gallon equivalent. EPA’s normalization to gas metrics.
This article uses kWh/mile primarily; kWh/km equivalent shown when relevant.
What’s normal
A rough guide to efficiency by vehicle type.
Very efficient sedans (Tesla Model 3, Hyundai Ioniq 6, Lucid Air): 0.22-0.27 kWh/mile (140-180 Wh/km).
Standard EVs (most sedans and crossovers): 0.28-0.35 kWh/mile (175-220 Wh/km).
Heavier SUVs / crossovers (Tesla Model X, Rivian R1S, Mercedes EQS): 0.35-0.45 kWh/mile (220-280 Wh/km).
Large EVs (Ford F-150 Lightning, GMC Hummer EV, large luxury SUVs): 0.45-0.60 kWh/mile (280-375 Wh/km).
Trucks under load: higher still; varies dramatically with cargo.
For context, a gas car at 30 mpg uses about 0.11 gallons/mile = 3.7 kWh equivalent per mile. EVs are 10-15x more energy efficient than gas vehicles at the wheel, though this becomes 3-5x more when factoring in grid power generation efficiency.
What affects efficiency
A list of factors with rough magnitude.
Speed
The biggest single factor for highway driving. Air resistance scales with speed squared.
- 50 mph (80 km/h): efficient baseline.
- 65 mph (105 km/h): ~20-30% more energy than 50.
- 75 mph (120 km/h): ~40-60% more energy than 50.
- 85 mph (135 km/h): ~70-100% more energy than 50.
This is why range estimates drop dramatically when you drive fast on highway.
Temperature
Cold weather hurts efficiency.
- Mild conditions (15-25°C / 60-77°F): baseline.
- Cold (-5 to 5°C / 23-41°F): 15-30% worse.
- Very cold (below -10°C / 14°F): 30-50% worse.
Hot weather is less impactful (air conditioning uses less energy than heating), maybe 5-15% worse in extreme heat. The cold-weather charging explainer (coming soon) covers why low temperatures hit both range and charge speed.
Cabin heating / cooling
A heat pump (in modern EVs) is much more efficient than resistive heating. The difference is significant.
- Heat pump in cold weather: maybe 1-2 kW continuous draw, modest range impact.
- Resistive heating in cold weather: 3-5 kW continuous draw, significant range impact.
Pre-conditioning the cabin while plugged in (using grid power) helps a lot — start the trip warm without using battery to warm.
Driving style
Smooth driving is more efficient than aggressive.
- Gentle acceleration, anticipation, regenerative braking: baseline.
- Aggressive starts, hard braking: 10-20% worse.
- Track-style driving: dramatically worse (50%+).
The biggest gains: smooth acceleration and using regenerative braking effectively (lifting off accelerator early).
Tires and rolling resistance
Low-rolling-resistance tires are designed for efficiency. Aftermarket tires (especially all-terrain or off-road) can be 10-20% less efficient.
Tire pressure matters too — underinflated tires are notably less efficient.
Cargo and passengers
Each ~100 kg of additional weight adds maybe 1-2% energy use (more on inclines, less on flats).
Roof racks especially hurt efficiency due to aerodynamic drag — 10-20% worse with a loaded roof rack.
Terrain
Hills cost energy going up; some recovers via regen going down. Net effect: hilly routes are typically 5-15% less efficient than flat.
HVAC system efficiency
Heat pumps (now standard in most newer EVs) are 2-3x more efficient than resistive heating systems used in older EVs.
If you’re shopping for an EV and live in a cold climate, prioritize one with a heat pump. The heat pump vs resistive heating comparison (coming soon) goes deeper on the tradeoffs.
EPA range vs real-world range
EPA published range numbers come from standardized testing — specific speeds, temperatures, conditions. Your real-world range may differ.
A few notes:
- Highway driving typically achieves 80-90% of EPA range.
- City driving often exceeds EPA range (lower speeds, regenerative braking).
- Winter typically 60-75% of EPA range.
- Heavy cargo / passengers reduces from EPA.
Plan trips assuming the lower end of these ranges. Discovering your “300 mile EPA range” is actually 220 miles in current conditions when you’re 50 miles from a charger is a bad surprise.
How to maximize efficiency
A practical list for getting the most range from your EV.
Driving habits
Drive at moderate speed. 55-65 mph if you have the option. Highway 75+ mph dramatically reduces range.
Smooth acceleration. Strong starts use significant energy. Gradual is more efficient.
Anticipate and coast. Lift off the accelerator early. Let regenerative braking recover energy.
Use one-pedal driving. Most EVs support strong regenerative braking (coming soon) that recovers energy when you lift off the accelerator.
Plan elevation. Going downhill recovers energy; going uphill burns it. Mixed terrain averages out somewhat but going down a long descent at high SOC may exceed regen capacity.
Pre-conditioning
Pre-heat or pre-cool the cabin while plugged in. Uses grid power, not battery. Saves the energy you’d otherwise spend in the first 15-20 minutes of driving warming up.
Pre-condition the battery for fast charging. As discussed elsewhere, faster fast charging means less time and possibly less distance traveled at lower speeds.
Maintenance
Keep tires inflated correctly. Under-inflation hurts efficiency. Most automakers publish target pressures.
Use efficient tires when replacing. Low-rolling-resistance options exist; not always the most exciting tires but they pay back in range.
Remove unnecessary cargo and roof racks when not needed.
Climate
Pre-cool / pre-warm the car while plugged in — use grid power not battery.
Park in moderate-temperature locations when possible — battery sitting hot or cold preconditions inefficiently.
Use seat heaters instead of cabin heating when possible — much more efficient.
Trip planning
Plan charging stops at the right SOC. Charging from 20% to 70% is fastest. Don’t try to get to 100% at fast chargers — last 20% is slow.
Use route planning tools. ABRP, in-car navigation. They optimize speed/range tradeoffs. See the road trip planning guide (coming soon) for putting these buffers into practice.
Account for elevation. Going uphill on a long route burns energy.
Allow buffers. Aim to arrive at chargers with 10-20% SOC, not 1-2%.
What the numbers mean for cost
EV efficiency translates to cost per mile.
At $0.15/kWh (home rate) and 0.30 kWh/mile efficiency:
- Cost per mile: $0.15 × 0.30 = $0.045/mile.
- For 12,000 miles/year: $540/year in electricity.
At $0.40/kWh (public DC fast) and 0.30 kWh/mile:
- Cost per mile: $0.40 × 0.30 = $0.12/mile.
- 12,000 miles/year: $1,440/year if all DC fast.
For comparison, a gas car at 30 mpg and $4/gallon gas:
- Cost per mile: $4 / 30 = $0.133/mile.
- 12,000 miles/year: $1,600/year.
EVs are significantly cheaper per mile when charging at home; comparable or somewhat cheaper when charging at public DC fast.
The honest summary
EV efficiency is measured in kWh per mile (or per km). Typical values are 0.25-0.40 kWh/mile for sedans, more for SUVs and trucks. Speed is the biggest single factor for highway driving; temperature is the biggest factor in winter. EPA ranges are achievable in good conditions; plan for less in cold weather or highway driving. Understanding your efficiency under your conditions lets you plan trips accurately and use your EV optimally.