  Self-consistent hybrid N-body and SPH simulations are used to give a new and
coherent interpretation of the main features standing out from the HI and CO
longitude-velocity observations within the Galactic bar. In particular, the
traces of the gas associated to the Milky Way's dustlanes can be reliably
identified and the 3-kpc arm appears as a gaseous stream rather than a density
wave. The bar and the gaseous nuclear ring in the simulations undergo
synchronised and long lived oscillations around the centre of mass, and the gas
flow always remains non-stationary, suggesting a transient nature of the
observed gas kinematics.
