We perform a general model-independent analysis of bto ctau {overline{nu}}_{tau } transitions, including measurements of ℛD, ℛD∗, their q2 differential distributions, the recently measured longitudinal D* polarization {F}_L^{Dast } , and constraints from the {B}_cto tau {overline{nu}}_{tau } lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected bto ctau {overline{nu}}_{tau } observables, such as the baryonic transition {Lambda}_bto {Lambda}_ctau {overline{nu}}_{tau } , the ratio ℛJ/ψ, the forward-backward asymmetries {mathcal{A}}_{mathrm{FB}}^{Dleft(ast right)} , the τ polarization asymmetries {mathcal{P}}_{tau}^{Dleft(ast right)} , and the longitudinal D* polarization fraction {F}_L^{Dast } . The latter shows presently a slight tension with any new-physics model, such that an improved measurement could have an important impact. We also discuss the potential change due the very recently announced preliminary {mathrm{mathcal{R}}}_{mathcal{D}left(ast right)} measurement by the Belle collaboration.