The rise of the Electric Vehicle - Cyclists new danger?

Can't say I've ever been surprised by an electric car - as has been said - its the road noise more than the engine noise.

I was surprised by the shadow of a double decker bus looming over me before I'd heard it. 

I think it was a combination of low sun, a hill and a headwind drowning out its engine. 

We Have a 18 Leaf.  The car emits a sound below 30 mph to aid pedestrians and other users to hear it.  It is very quiet at slow speeds.  Once going 25mph+ tyre noise makes most of the noise like any car. 

I think its a question on relying on all your senses - you can see something before you hear it and I certainly listen on approach to blind junctions. Of course that doesn't account for other cyclists so it's still a case of approaching with caution. I think over 20mph road noise from tyres is loud enough, particularly in quiter environments. There's bloke with a monster eBike where I live and that thing sounds like turbo trainer as it goes past.

It's like that Garmin rear radar thingy. What are you supposed to do with the information that there is a car behind you?

My experience has been that there is very little noise from EVs when they are moving at slow speeds.  I've been surprised by a Prius in a car park more than once. 

When out on the open road, they make plenty of noise, a surprising amount, in fact.  This is through contact between the road surface and tyres.  Very recently I was aware of a car approaching from behind and as it passed me I realised it was a Nissan Leaf.  I'd heard it coming well before it was close by and the sound was virtually the same as a petrol car.

We've become used to motorised vehicles making a noise and many people don't bother to look as a result.  If you can't hear it, it's not there.  It may take time but we'll soon work it out that we have to use our eyes and ears to cross a road safely.  This way, it will also benefit cyclists - or should we have noises added to our bikes?