40 vs 60 kWh Battery: When the Bigger One Pays Off

Two versions of the same electric car often sit side by side on the forecourt. One carries about 40 kWh of battery, the other about 60. The extra 20 kWh buys about 50 per cent more range. That holds at any speed and in any weather. What changes is the price you pay for it. And what your government does about the choice. In the UK those two pull in opposite directions.

Table of contents

• The quick answer
• What the extra range really gives you
• Does the extra weight eat the gain?
• What 20 kWh costs
• The UK, and five neighbours
• Which one to buy
• Common questions
• Sources and dates

The quick answer

What the extra range really gives you

Every range figure here uses usable capacity, the part of the pack the car lets you use. The consumption figures come from owner trip computers. Those are measured at the battery. Nothing here has been converted.

The ranges are rounded to whole kilometres, so subtracting the columns can be a kilometre out from the last one.

The share never moves. Sixty divided by forty is 1.5, whatever the car is doing.

The kilometres do move. At 13.1 kWh/100 km the bigger pack adds 153 km. At 21.0 it adds 95 km. Work the car harder and the prize gets smaller in kilometres.

Now count charging stops instead. Assume a 600 km drive. The car starts full. Every stop runs from 10 per cent to 80 per cent, so each one puts back 70 per cent of the pack. The car arrives close to empty.

Three things are true at the same time. The percentage sits at 50. The extra kilometres shrink as you drive faster. The stops you skip grow.

Which one matters depends on you. If your long drives are rare and you charge where you park, look at the kilometres. If you cover 600 km at motorway speed several times a year, count the stops.

Cold weather and motorway speed both push consumption up. On most cars measured, the cold costs more than the speed. The numbers live in a separate post: WLTP against real range.

A "40 kWh" car may not hold 40 kWh. Makers quote two figures. Gross is the whole pack. Usable is what you get. The gap between them is not a fixed share.

Across those four cars the buffer runs from 2.5 to 6.7 per cent. So look up your own car rather than trust a rule of thumb. Two sources agree on all four rows above. They do not agree on the MG4. The site ev-database gives 50.8 and 61.7 kWh usable. ADAC gives 49.0 and 59.5. For the Renault packs we found no maker figure for gross capacity at all.

Does the extra weight eat the gain?

A bigger pack is heavier. A heavier car uses more energy. Here is what the brochure figures show, for the same model in two battery sizes.

Those are WLTP combined figures in kWh/100 km, from ADAC's pages for each version.

On paper the bigger-battery cars are not worse. But makers fit the most efficient wheels and tyres to the long-range version. They do that to push its headline range up. Motor power differs too. So no row here isolates the weight.

There is one measured test of the same model in both sizes. ADAC ran the Nissan Leaf through its Ecotest at the same charging setting. The 40 kWh car used 22.1 kWh/100 km. The 62 kWh e+ used 22.7. The bigger battery used about 3 per cent more. That test carries a motor difference too, 110 against 160 kW. We also could not pin down the two test dates.

Where that leaves it. The extra weight is not free. The effect is small. We cannot tell you the weight worry is wrong, because nothing we found tests it cleanly.

One row needs care. The MG4 with the bigger pack is only about 16 kg heavier. Its chemistry changes from LFP to NMC. The Luxury trim of the same pack change gains 40 kg. The 64 kWh car also has a stronger motor.

If you check ADAC yourself, watch which test you are reading. The Kona page for the small pack shows a WLTP figure. The page for the large pack shows a WLTP figure and an Ecotest figure. Compare across the two tests and you invent a penalty that is not there.

What 20 kWh costs

BloombergNEF surveys battery prices every year. The 2025 survey came out on 9 December 2025.

Twenty kWh at $99 comes to about $2,000. Treat that as an order of size rather than a build cost. A pack price also covers the case, the cooling, the electronics and the assembly. None of that grows when you add cells. So 20 more kWh of cells cost less than 20 times the pack price. We could not get the split between cell and pack. BloombergNEF keeps it behind a client paywall. The $99 is also a world average dominated by Chinese production. We are holding it against European prices.

Now what the market charges. These are used listings, including demonstrators, read on 30 September 2026. The medians are ours, taken from the first listings each search returned.

The same 20 kWh, in the same two cars, sells for GBP 450 in Britain and about $2,700 in Ukraine.

The UK, and five neighbours

The UK is the one market here where the two levers push opposite ways. A bigger battery can add GBP 2,200 of tax on one car. On another it adds GBP 2,250 of grant.

The tax side. The Audi Q4 e-tron crosses GBP 50,000 on the battery step. Same trim, same rear-wheel drive. The 63 kWh Sport is listed at GBP 46,600. The 82 kWh Sport is listed at GBP 50,960. Crossing GBP 50,000 triggers the Expensive Car Supplement.

Two warnings go with that. Our prices are secondary. They come from fleetworld and carwow, because Audi UK's own configurator would not load for us. Carwow lists the smaller car at GBP 46,260 instead, so the two sites disagree. The figures above are fleetworld's throughout. The second warning matters more. The 82 kWh car also steps from 150 kW to 210 kW of motor power. The battery is not doing this on its own.

What the supplement costs. GBP 440 a year for five years, starting from the second vehicle licence. That is GBP 2,200. The standard rate for a car outside it is GBP 200 a year. The first year is GBP 10. The supplement applies from 1 April 2026, to a list price over GBP 50,000. It covers every zero-emission car registered on or after 1 April 2025. Cars registered before that date never pay it. The figure is GBP 440, not the GBP 425 still circulating.

The grant side. We re-read the government's Electric Car Grant list on gov.uk on 30 September 2026. It puts the Renault 5 with the 52 kWh battery in Band 1. The same car with the 40 kWh battery is in Band 2. The Nissan Micra is listed the same way. Band 1 is worth up to GBP 3,750. Band 2 is worth up to GBP 1,500. So the bigger battery is worth GBP 2,250 more to the buyer.

We offer no explanation for that. The published criterion is the carbon intensity of where the car and its battery are made. It counts where the battery was produced for 70 per cent and final assembly for 30 per cent. It says nothing about capacity. Our first guess was two different cell factories. Renault says both Renault 5 packs use NMC chemistry. It also says it decided to build them at Douai. So we report what the list shows and what the rule says. We claim no cause.

One more thing a buyer should know. The grant caps the recommended retail price at GBP 37,000. Related versions of the same model have a GBP 42,000 ceiling. Both numbers sit on the guidance page written for manufacturers. We fetched the consumer page on 30 September 2026. The cap is not on it. Someone reading the page written for them would not know a cap exists.

What the used market charges. Very little. At Motorpoint on 30 September 2026, a 2021 Leaf e+ Tekna with the 62 kWh pack was GBP 11,199. The 2021 Tekna with the 40 kWh pack was GBP 10,749. That is a 4 per cent premium. The same two cars carry a 22 per cent premium in Ukraine. Our UK figure rests on 44 and 15 cars across two curated retailers. Read it as those forecourts, not a national index.

An owner's view. The best argument we read for the big pack is about time rather than distance. An owner on the MG EVs forum described hitting bad traffic with the small battery. You cannot cut the charging stop short and get going again, they wrote, because the car needs the time it needs. The same forum carries the other side. The long-range MG4 cost GBP 2,500 more than the standard one. That buys a lot of public charging.

Five neighbours, for comparison.

Which one to buy

Buy the smaller battery if three things are true. Most of your days are short. You can charge where you park. Your long drives happen a few times a year. On a used Megane in Germany the gap is about EUR 7,200. That pays for a great deal of charging.

Buy the bigger battery if any of these fit you:

• You cover long motorway stretches at 120 to 130 km/h. That is where the stop count changes most.
• You cannot charge at home. The bigger pack buys you fewer trips to a public charger.
• Your trips run to a timetable. The stop you cannot shorten is the real cost of the small pack.
• The price gap is small. GBP 450 on a used Leaf is small enough to ignore.
• You are buying a Renault 5 or a Nissan Micra new in the UK. The 52 kWh version sits in the higher grant band.

Check the GBP 50,000 line before you order a new car. The bigger battery can push a version that sits just under it over the line. That costs GBP 2,200 across five years.

Weighing two different used cars rather than two battery sizes? We compared a pair here: used Model Y against Enyaq. You can also line up any two versions in our comparison tool.

Common questions

How fast do these batteries lose capacity?

Slower than most buyers fear. ADAC ran a VW ID.3 with a 77 kWh pack to 220,000 km. It still measured 89 per cent of the original capacity. Its measured range at 172,000 km was 425 km, against 438 km when new. ADAC's engineers put 70 per cent capacity at roughly 200,000 km or ten years. A 2014 BMW i3 held 86 per cent after five years and 100,000 km.

What does the battery warranty actually promise?

Each maker publishes its own terms.

Nissan is the odd one out, and a used Leaf buyer should know it. A bar gauge is a coarser test than a measured percentage. It is also the less generous of the two. We checked that wording in Nissan UK's own warranty book. We did not re-verify the other three rows ourselves.

What does a replacement battery cost?

We could not find a current European price list. ADAC publishes no euro figures, and says makers are still reluctant to give them. The only European figures we found come from a parts-price survey in Auto Strassenverkehr, issue 8 of 2021. It gives EUR 10,306 for a Leaf 40 kWh pack and EUR 15,516 for the 62 kWh one. Those are 2021 parts prices. On BloombergNEF's own series, pack prices have fallen from $137 per kWh in 2020 to $108 in 2025. A whole-pack swap outside warranty is rare in any case. Workshops normally repair at module level.

I am buying used. Does the Expensive Car Supplement hit me?

Only if two things hold. The car was first registered on or after 1 April 2025. Its list price when new was over GBP 50,000. The supplement then runs for five years from the second vehicle licence. So a car bought in its third year still has some of it left. Cars registered before 1 April 2025 do not pay it at all.

Is there a price cap on the Electric Car Grant?

Yes. GBP 37,000 on the recommended retail price. Related versions of the same model have a GBP 42,000 ceiling. Both numbers sit on the guidance page for manufacturers. We fetched the consumer page on 30 September 2026. Neither figure appears on it.

I drive 30 km a day. Do I need 60 kWh?

Not for that. A 40 kWh car still covers 190 km at 21.0 kWh/100 km. That is motorway pace. Your worst week decides this, rather than your average day. If that week comes round four times a year, the smaller pack is still the cheaper answer.

Sources and dates

All figures verified 30 September 2026.

• Battery prices: BloombergNEF 2025 Lithium-Ion Battery Price Survey, published 9 December 2025.
• Consumption log at 13.1 kWh/100 km: QualEnergia, Leonardo Berlen, 7 January 2025. One owner, 3,335 km in November and December, mild season, partly charged from solar.
• Consumption logs at 17.6 and 21.0: forums.automobile-propre.com topic 73333. The 1,365 km mixed log is dated 8 April 2026, the steady 130 km/h figures 2 March 2026.
• Measured test, brochure figures and degradation: ADAC Ecotest, ADAC's pages for each version, and the ADAC long-term test of the VW ID.3.
• Usable against gross capacity: ADAC and ev-database, which agree on all four rows quoted.
• UK vehicle tax: DVLA leaflet V149, applying on or after 1 April 2026, updated 1 July 2026.
• UK grant: gov.uk/plug-in-vehicle-grants/cars, re-read 30 September 2026. The price cap comes from the Department for Transport guidance page for manufacturers.
• Audi Q4 e-tron prices: fleetworld.co.uk and carwow. Secondary sources. Audi UK's own configurator was not readable for us.
• Used prices: Motorpoint and one other UK retailer, 44 and 15 cars, 30 September 2026. German and Ukrainian listings were read the same day.
• Owner comments: the MG EVs forum. We could not recover usernames or dates for individual posts.
• Warranties: each brand's own published terms. The Nissan wording comes from its UK warranty book.
• Ukraine excise: Tax Code of Ukraine article 215, subclause 215.3.5-1. Clause 190.1 covers the VAT charged on the excise. Confirmed on customs.gov.ua.
• Other markets: KraftStG section 3d for Germany, Wet MRB 1994 for the Netherlands, service-public.gouv.fr for France, and DPR 39/1953 article 20 with L. 449/1997 article 17 comma 5 for Italy.
• Replacement pack prices: Auto Strassenverkehr, issue 8 of 2021, republished by t-online.