[en] We present the results of a synthetic spectral analysis of the far-ultraviolet archival International Ultraviolet Explorer, Hubble Space Telescope (HST), and FUSE observations of the fast old nova V603 Aql, obtained some 90 years after its 1918 nova outburst. Our analysis utilizes the new Hubble fine guidance sensor parallax distance for this nearly face-on old nova, a high white dwarf (WD) mass, and a low reddening. Our analysis includes non-truncated optically thick accretion disks since V603 Aql is neither a polar nor an intermediate polar. Our synthetic spectral modeling of the FUSE and HST spectra analyzed separately indicate a mass transfer rate of $\stackrel{\dot{}<!--\; ??\; -->}{M}=1.5-<!--\; ???\; -->2.2\times <!--\; ??\; -->{10}^{-<!--\; ???\; -->9}{M}_{\odot <!--\; ???\; -->}$ yr⁻¹ for the FUSE and HST spectra, respectively, assuming a WD mass of $1.2M_{\odot <!--\; ???\; -->}$. The mass accretion rate also depends on the assumed WD mass and increases by a factor of two for a WD mass of $0.8M_{\odot <!--\; ???\; -->}$. Combining the FUSE and HST spectra lead to the same results. Potential implications are discussed.