Quick answer
There is no single percentage by which every electric car loses range on a highway or in an Indian summer. Speed, temperature, air-conditioning use, traffic, load and the particular vehicle all matter. Use the correct model's range information and your own measured consumption, then plan charging stops with a reserve.
A certified range figure is not a promise for a fully loaded summer road trip. Nor does the difference between certified and manufacturer-estimated real-world range measure the effect of heat alone. Those numbers may use different methods and conditions.
Start by identifying the number you are comparing
An EV advertisement may show certified range, an estimated real-world figure or the dashboard's remaining-distance estimate. These are not interchangeable. Before comparing two numbers, identify the battery version, test basis and charge window.
Tata's published driving-range declaration describes its C75 disclosure as a near-real-world range that 75 per cent of customers can expect, based on historical usage data. That is a manufacturer estimate with a stated basis, not a guarantee that every journey will achieve it.
For example, Tata's September 2024 Nexon.ev 45 kWh release quoted 489 km under its stated Urban plus Extra Urban basis and a C75 range of 350–370 km. These are dated figures for that release, not a current recommendation or a summer test. Their difference must not be presented as a measured temperature penalty.
When buying today, obtain the current brochure for the exact version. A familiar model name can cover several batteries, wheel sizes and equipment combinations. Keep the brochure date with your notes so a later specification change does not quietly alter the comparison.
Why the highway can use more energy
At higher road speeds, aerodynamic resistance becomes an important energy demand. A quiet cabin can make sustained speed feel effortless, but the energy display may tell a different story. Strong acceleration and repeated speed changes can also affect consumption.
City use and highway use involve different patterns. Urban driving may offer more chances for energy recovery during slowing, while an open road may involve prolonged higher speeds. However, slow traffic with a long period of air-conditioning use is not automatically the most efficient situation either.
Do not treat a city result as a highway forecast. Ask for consumption evidence at a realistic, lawful cruising speed, with climate control and passenger load described. A short demonstration around the showroom cannot establish how the vehicle will perform on an intercity route.
Why summer changes the calculation
Cooling a hot cabin and maintaining battery operating conditions require energy. Outside temperature, parking exposure and journey duration influence the result. A short drive after a long period in the sun can have a different consumption pattern from a longer trip after the cabin has cooled.
Mahindra's BE 6 manual identifies temperature, weather, air-conditioning or heater use, load, terrain and driving pattern among range factors. It also warns that extreme ambient conditions, including temperatures above 35°C, can adversely affect range. This is model guidance, not a universal percentage for every EV.
Avoid adding several internet percentages together. A claimed highway penalty and a claimed summer penalty may already include overlapping conditions. Applying both mechanically can produce an estimate with no sound test basis.
Compare like with like
| Detail | Record this | Why it matters |
|---|---|---|
| Vehicle | Model, battery and wheel version | Similar names can hide different specifications |
| Charge window | Starting and ending percentage | A partial-battery trip is not a full-charge test |
| Route | Distance, direction and elevation | An uphill journey differs from its return |
| Speed | Typical cruising and traffic pattern | Average speed alone can hide long stops |
| Weather | Temperature and conditions | Heat, rain and wind can change demand |
| Cabin | AC setting and passengers | Comfort needs and load affect the comparison |
| Result | Energy use and distance | Helps separate consumption from a changing prediction |
Use these details when reading an owner report. A range screenshot without its route, weather or charge window offers limited help. Several repeat journeys under similar conditions are more useful than one exceptional result.
A calculation that explains the relationship
Suppose a hypothetical car has 50 kWh of usable energy. At an assumed consumption of 15 kWh per 100 km, the arithmetic full-window distance is about 333 km. At an assumed 20 kWh per 100 km, it is 250 km. That represents a 25 per cent reduction in calculated distance.
These are invented inputs for explaining the calculation. They are not measured figures for a named car and do not establish a standard summer loss. The point is that range changes when energy consumption changes, even though the battery's nominal specification remains the same.
For a journey, use the energy between your intended departure level and arrival reserve, not the full usable capacity. If the same hypothetical vehicle leaves at 90 per cent and you plan to arrive at 20 per cent, that 70-percentage-point window represents about 35 kWh under the simplified assumption.
At the assumed 20 kWh per 100 km, that gives approximately 175 km before the planned reserve. Allow for uncertainty rather than using this arithmetic to justify arriving at the charger with almost no flexibility.
The dashboard estimate is a forecast
Remaining kilometres can change as the vehicle updates its estimate. Recent driving and conditions may influence the displayed prediction according to the model's system. A change in predicted distance is not by itself a measurement of permanent battery deterioration.
Watch the battery percentage, the planned route and actual consumption where available. If a new highway leg consumes more energy than expected, revise the charging plan early. Do not continue towards an unsuitable stop simply because the initial dashboard number looked comfortable.
A persistent warning or unexplained change needs professional diagnosis. Keep dates, route details and relevant displays for the service centre. A workshop can investigate a fault; an isolated range screenshot cannot identify its cause.
Build a useful record without running the battery low
Use an ordinary journey with safe charging options. Record departure and arrival percentage, distance, consumption if displayed, temperature, load and climate-control use. Repeat when practical, using the same route direction and broadly similar conditions.
Do not conduct an empty-battery experiment on a public road. A useful ownership record does not require reaching zero. A normal partial-charge journey can help you understand consumption while preserving a sensible reserve.
Keep wall-charger electricity separate from the car's driving-energy display. Charging losses and measurement boundaries can make these quantities differ. Use each for its proper purpose: the bill for electricity spending, and the relevant vehicle display for understanding driving consumption.
Improve efficiency without sacrificing comfort or safety
Keep tyres at the manufacturer's specified pressures for the load. Do not overinflate them to chase a range figure. Remove unnecessary luggage and unused external carriers when appropriate, while retaining required safety equipment.
Drive smoothly, leave a safe following distance and respect speed limits. Use the vehicle's efficiency mode when suitable. Kia India's EV driving guidance recommends ECO mode for driving distance, but any mode still requires the driver to respond safely to road conditions.
Use climate control sensibly rather than switching it off when occupants need cooling or the windows need clearing. If the car supports cabin preparation while plugged in, follow its manual and charging instructions. Do not assume an overseas feature is available on the Indian version.
Plan the summer highway stop before departure
Identify a compatible primary charger and an alternative. Check access hours, connector, payment method and current operator information. The backup should be reachable with the reserve you have allowed, not merely appear somewhere on the map.
Allow for detours, waiting and charging time. A family journey needs practical facilities as well as electrical compatibility. Confirm whether a destination charger is genuinely available to you and whether it can replenish enough energy during your stay.
Reassess after an early part of the journey if consumption differs from your assumption. Stopping sooner is often simpler than trying to recover a plan built around an optimistic range estimate. Never make a risky manoeuvre or stop in an unsafe location to save electricity.
Frequently asked questions
Does every EV lose the same range in summer?
No. Vehicle design, temperature, cabin cooling, trip length and driving conditions differ. Use model-specific information and measured consumption rather than a fixed national percentage.
Is the certified-to-real-world gap the summer loss?
No. Different test methods and driving conditions can explain that gap. A weather comparison requires otherwise comparable tests, not two differently defined headline figures.
Should I switch off AC to reach a charger?
Do not compromise occupant health, visibility or safe driving. Plan an earlier suitable stop and keep a reserve. Climate-control settings should remain appropriate for the conditions.
Does a lower dashboard estimate prove battery damage?
No. It can reflect changed operating conditions or the system's prediction. Persistent unexplained changes or warnings need authorised diagnosis and supporting records.
How much reserve should I keep?
There is no single suitable margin for every route. Allow enough for realistic uncertainty and a reachable backup, using your car's guidance and the journey's charging options.
Check your own route before choosing an EV
Ask for the exact battery specification, current range disclosure and a suitable test drive. Compare the car against your longest regular journey with climate control and passengers, then identify charging stops. Choose on a workable routine, not the largest brochure number alone.