Comparing the cost of driving a diesel car to an electric car

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

14 September 2025

Joseph Wanyoike is not convinced that electric vehicles (EVs) have a future… “especially not in Kenya with its high cost of electricity”. He challenged me to compare the running cost of internal combustion engine to that of an EV, adding: “I drive a 2,000cc diesel powered family car…[that]…averages 17km/litre on most trips. How much better can electric cars be?”

Even though kilometres per litre is the popular way of expressing fuel consumption of cars, it is actually an inverted quantity – it is upside down. Think about it: we say that a car that drives, say, 10km/L consumes MORE than the one going 17km/L; yet, 10 is a SMALLER number than 17!

The better [and, in my view, more correct] way is to state the volume consumed per kilometre. Some cars have built-in displays that show the volume consumed per 100km. Thought this is better, I find it a little cumbersome: I think it should be expressed as a volume of fuel per one kilometre.

Now Joseph’s car averages 17km/L; this works to about 0.059L/km – admittedly, this is an awkward value. It can be polished by converting to the litres to millilitres. Thus, 59ml/km. It is now very easy to work out how much money Joseph is spending on fuel for every km of driving – just multiply it by the cost per litre.

The price of diesel in Nairobi is about Sh172 per litre, so, the 0.059L/km (59ml/km) would cost about Sh10.15/km. I checked the tested performance of a comparable EV and found that they average about 5km/kWh which translates to 0.2kWh/km.

Thus, at the current “high” electricity price of Sh28/kWh, the cost driving an EV comes to about Sh5.60/km. This is about a half of the figure for an efficient diesel-powered car. The EV wins by a large margin.

I expect that some readers will protest that I should really be looking at the total cost of ownership which includes purchase price, insurance and maintenance. Well, since most fuel-powered cars in Kenya are used imports from Japan that are seven years old when they land here, their buying price is very low – less than half that of a new EV.

With the low price also comes lower insurance cost, but slightly higher repairs and maintenance costs. So, it isn’t really fair to compare total cost of ownership of EVs to fuel-powered cars in the Kenyan market. However, looking at how the number of electric motorcycles on our streets is increasing, I still believe that it won’t take long before electric cars also become popular.