HP has measured engine power for years – but has its day come?

We’re all familiar with the merits of a 250hp engine alongside 200hp one. We know a 75hp supermini will be cooking, but a 100hp one will be mildly tasty; a 150bp one, amusing.

But with the coming of electric cars, the merits of using hp are numbered. Everything important in electric cars is a measure of energy in watts – or, to make the numbers more manageable, kW (1000 watts is a kW).

Key to this is the output of the battery, and how much power it produces. It’s simply not measured in horsepower!

The Nissan LEAF, for instance, has a 24kWh battery capacity. That means, it will sustain a 24kW output for 1 hour. From this, range can be calculated – and as range is THE fundamental stumbling block for EVs at the moment, any confusing and pointless conversions here are just not a good idea.

So, before electric cars become big news, maybe it’s time we got ourselves and others fluent in kW with combustion cars? Thus, easing the contextual mental comparisons when EVs come en masse?

It won’t be easy, or at all welcomed. There will be resistance. Anything Euro-speak usually is. But, whereas litres per 100km is a really big step too far (if also more logical: a lower figure means it uses less, so is better…), hp to kW is easier to work out.

Europeans already use kW. And, granted, it causes journos no end of head-scratching at international press conferences, until we see the UK-converted press pack. 66kW 1.6 petrol? What on earth does that mean? 90hp, that’s what. 135kW sounds pretty lukewarm, until you find out it’s actually 184hp. And so on.

The formula, though, is simple. 1hp = 0.746kW. Or, 1kW = 1.341hp.

So, journos, here’s a plan: why not explain to readers what you’re doing, and why, and then start putting dual figures in tests?

Mind you, mph to km/h is also a direct conversion, and that hasn’t happened yet, either. Are we thus destined for a future of electric motor conversions, too? After all, which sounds more marketable – a 150kW MINI E, or a 204hp one..?

+ Would you be happy to use kW instead of hp?
+ Does the logic of moving to metric make sense?
+ Do you find it easy to put electric car kW output into context?