Can f (Q ) gravity challenge Λ CDM ?

We study observational constraints on the nonmetricity f (Q )-gravity which reproduces an exact Λ CDM background expansion history while modifying the evolution of linear perturbations. To this purpose we use cosmic microwave background (CMB) radiation, baryonic acoustic oscillations (BAO), redshift-space distortions (RSD), supernovae type Ia (SNIa), galaxy clustering (GC) and weak gravitational lensing (WL) measurements. We set stringent constraints on the parameter of the model controlling the modifications to the gravitational interaction at linear perturbation level. We find the model to be statistically preferred by data over the Λ CDM according to the χ² and deviance information criterion statistics for the combination with CMB, BAO, RSD and SNIa. This is mostly associated to a better fit to the low-ℓ tail of CMB temperature anisotropies.