If I had an electric car, I'd charge it overnight. I don't get different pricing at different times. There has been talk of introducing that for decades now (in Germany), but I'm not sure it is coming soon, nor that I'd like it. Probably, it would become just more expensive when I need it most, without being able to change my usage patterns much.
There is no "talk of introducing this for decades" since it exists since decades.
Here's all you need to know: https://de.wikipedia.org/wiki/Niedertarifstrom
Why?! Two-rate meters have been around for decades, long before they went digital.
Never actually used an economy 7 tariff myself so I don't know the details but the point is most houses in the UK aren't equipped to have one. However a home-owner choosing to install a charging point for an electric vehicle will probably switch to a suitable metering setup for economy 7 whilst they're at it.
All homes in Britain will have smart meters installed by 2020:
https://www.smartenergygb.org/en/smart-future/about-the-roll...
These support Economy 7, as well as whatever other variable tariffs that energy companies dream up in the future.