We present the first self-consistent 3D barred model of the Milky Way including gas, as an evolved stage of an unsymmetrised N-body simulation with axisymmetric initial conditions (fig.1). The corotation lies at about 4 kpc and the central gas particles have condensed into a nuclear ring/disc. Distortions of the bar and other odd modes in the stellar distribution (a) affect the gas flow by producing one-side gas voids (b) and instabilities of the nuclear component like tilting, warping and off-centering (c-d). These peculiarities may help to reproduce the intriguing asymmetries and densely populated “forbidden” regions in the Galactic HI and CO (l – v) maps (e-f). More details are given in the proc. of IAU Coll. 157 “Barred Galaxies”.