It's not about packaging the EV powertrain - it's how you make the rest of the car around it. The Air is longer than all 5-series with the exception of the current one, which is often criticised for being the size of most 7 series. It's also got a similar profile to the one-bow design Mercedes used for the much criticised EQS and EQE. And the Air Pure pretty much starts in price where the (non-M) 3 series finishes...
... which of these characteristics would you carry over to a 3-er segment car?
Air vs G20...