More than 2.4 tons!
That's a token 20bhp less than the BMW XM Red Label, but there will be a bit less weight on the M5 side (emphasis on 'slightly', as the new fastest five will be anything but a light car).
Its curb weight should climb up to 2435 kg, with a significant part falling on the additional traction battery with a capacity of 18.6 kilowatt hours. We do not know the dynamics of the new M5, but we assume that it can accelerate from 0 to 100 km/h in about three seconds, and the maximum speed could be at the level of 250 km/h without a shifted limiter.