Two twelve-metre Foton city buses, both low-entry, both left-hand drive, both on a 5,900 mm wheelbase. One is $79,999 and one is $211,342.

The electric bus costs 2.6 times as much. It also weighs 2.1 tonnes more, seats fewer passengers and climbs worse. If you are writing the business case, those are the numbers you have to start from, not the ones you get to after the environmental argument.

This is not an anti-electric piece. Electric buses win on running cost in the right duty cycle. But the arithmetic has to be done honestly, and $131,343 is a lot of diesel.

The two buses side by side

What the $131,343 actually buys

Start with what you are not paying for, because it is the part people assume wrongly. You are not paying for more capacity. The diesel bus seats 39 plus driver against 36 plus three folding seats plus driver on the electric. You are not paying for more capability either: the diesel climbs at least 30% against at least 20% for the electric.

What you are paying for is the battery and everything around it. 382.53 kWh of CATL lithium iron phosphate, split between roof and rear mounting, with a dedicated cooling system (Songzhi single cold air conditioning integrated power battery cooling), battery heating, and a heptafluoropropane fire suppression system in the battery compartment and box.

That is a serious installation, and the structural work around it is real: the electric bus specifies a reinforced roof skeleton at the top-mounted battery location, additional connecting beams running front to rear between the roof and side wall skeleton, and reinforced passenger door and side window pillars to prevent cracking. Top-mounted batteries put mass high up and the body has to carry it.

You are also paying for a better body. The electric bus is a full load-bearing monocoque in high-strength steel with a stated design service life of ten years or 1.4 million kilometres. The diesel bus is semi-integral, with no published design life.

The premium buys a battery, a stronger body and a ten-year service life. It does not buy seats, capacity or gradeability — those all go down.

The three operating penalties, stated plainly

1. Weight

13,700 kg against 11,600 kg. That is 2,100 kg of battery and structure, and on a bus it comes straight out of payload. At roughly 70 kg per standing passenger, that is about 30 fewer passengers at the legal gross.

2. Seats

39 + 1 against 36 + 3 folding + 1. On a city route with high turnover, standing capacity matters more than seats, so this is less damaging than it looks — but for intercity, school or airport work where everyone sits, it is a real loss.

3. Gradeability

At least 30% against at least 20%. If your city has hills, or your route includes a steep ramp — a multistorey car park, a bridge approach, an airport tunnel — check this carefully. Twenty percent is a meaningful reduction.

Against those: the electric bus publishes an interior noise figure of no more than 72 dB(A) at 50 km/h, which the diesel sheet does not. For a city bus in a dense urban environment, cabin and kerbside noise is a genuine quality-of-service gain.

The running-cost case, honestly

Electric wins on three lines: energy per kilometre, maintenance, and brake wear. A battery-electric driveline has far fewer moving parts than an 8.3-litre diesel with an Allison automatic, no oil changes, no exhaust aftertreatment, and regenerative braking that saves friction material.

Diesel wins on three others: energy density, refuelling time, and infrastructure cost. A 230-litre tank is filled in minutes anywhere. A 382.53 kWh battery needs depot charging infrastructure you probably have to build, and the time it takes is time the bus is not earning.

So the payback question has three inputs you must supply locally: your electricity tariff per kWh, your diesel price per litre, and your daily route length. Without those three numbers, any payback claim — including any the manufacturer makes — is not a calculation, it is a marketing statement.

One further input that is easy to miss: battery degradation over a ten-year life, and the residual value of a ten-year-old battery. Get both in writing from the supplier, with a warranty that states a minimum retained capacity.

Where diesel still wins outright

Be honest about your situation. Diesel is the better purchase if your routes are long or unpredictable; if you have no depot charging and no budget to install it; if your grid is unreliable or expensive; if your topography is hilly; if you need maximum seating; or if your capital is constrained.

The BJ6123 also has two items worth noting on its own merits: an Allison T310 automatic with a built-in retarder, which is exactly what you want in stop-and-go city traffic, and air suspension, which the electric sheet does not publish. On a 12-metre bus doing twelve hours a day, both matter.

One caveat on the diesel: it is Euro II. That is an old certificate, and in a market tightening urban emissions it is the first thing that will be legislated against. If your city is moving to a low-emission zone, a Euro II bus has a shorter regulatory life than its mechanical one.

Which one should you buy?

Buy the BJ6123 diesel if capital is limited, routes are long or hilly, charging infrastructure does not exist, you need maximum seating, and your city does not restrict Euro II vehicles.

Buy the BJ6129 electric if you have fixed predictable daily routes inside the battery range, you can install depot charging, your electricity is cheap and reliable, your topography is flat, noise matters to your passengers or your regulator, and you are buying against a ten-year service life rather than a five-year one.

For most municipal operators in the markets these buses are specified for — Ethiopia and wider Africa — the honest answer today is that the diesel bus is the lower-risk purchase and the electric bus is the better one in five years. Buy accordingly.

What to ask the supplier before signing either order

On the electric bus, four questions matter more than any other. What is the warranted minimum retained battery capacity at ten years? What is the realistic range at full passenger load with air conditioning running, not at test conditions? What charging power does the depot need, and is that included in the $211,342? And what is the replacement cost of a battery pack outside warranty?

On the diesel bus, ask two. Is Euro II acceptable to your registration authority today, and will it be in five years? And what is the Allison T310 service interval and parts availability in your market — because an Allison automatic is excellent right up until the moment you cannot get it serviced.

Both buses publish a braking distance or regulatory statement at 30 km/h laden, but only the diesel gives a number: 9 metres. Ask the same figure for the electric bus. On a 19.5-tonne vehicle in a city, that is not an academic question.

One more practical point for the electric bus: the battery is split top-mounted and rear-mounted. Top mounting raises the centre of gravity and adds height — 3,350 mm against 3,200 mm. Check your depot door heights and your route for low bridges or overhead structures before you commit.

Compare the two buses side by side

12 m diesel city bus

Foton Auv BJ6123 City Bus

$79,999 · 245 hp · Cummins C245 8.3 L · Allison T310 · 39+1 seats · Air suspension

12 m electric city bus

Foton Auv BJ6129 Electric City Bus

$211,342 · 382.53 kWh CATL · Zero tailpipe · 36+3+1 seats · 10-year body life