I think the key is in the petrol caps.
In the original film there is only a short shot of the inside of a car which looks like an EV, but there's no way to tell if that is one of the cars in the "fields" shown elsewhere. In the shots of the presenter standing outside the cars you can see petrol caps on these cars.
Certainly the way the MG4 is built you couldn't say for sure looking at the cover over the charging port that that isn't an ICE fuel cap, not from its position. And there are ICE cars with petrol caps as big as that. But the petrol caps shown in the film were too small to be hiding a CCS charging port. They were obviously only big enough to get a petrol pump nozzle in.