Jaguar XE HSE MY20 2.0 litre petrol and Vauxhall Cavalier 1993 V6 2.5litre Petrol Auto
Yes, modern batteries do seem to fail completely suddenly - you can drive up quite normally, turn off the engine, come back in half an hour and the car is completely dead. I've had it happen to me.The battery had gone flat,never even considered that as i'd driven it there & had no previous clue/hints as to battery condition
A few years back batteries would always provide warnings of their demise - slow cranking when starting, headlights dimming as engine speed decreased etc.
This just doesn't happen any more.