  Photometric and spectroscopic observations of a slowly declining, luminous
Type Ia supernova (SN Ia) SN 2011hr in the starburst galaxy NGC 2691 are
presented. SN 2011hr is found to peak at $M_{B}=-19.84 \pm 0.40\,\rm{mag}$,
with a post-maximum decline rate $\Delta$m$_{15}$(B) = 0.92 $\pm$
0.03\,$\rm{mag}$. From the maximum-light bolometric luminosity, $L=(2.30 \pm
0.90) \times 10^{43}\,\rm{erg\,s^{-1}}$, we estimate the mass of synthesized
\Nifs\ in SN 2011hr to be $M(\rm{^{56}Ni})=1.11 \pm 0.43\,M_{\sun}$. SN 2011hr
appears more luminous than SN 1991T at around maximum light, and the absorption
features from its intermediate-mass elements (IMEs) are noticeably weaker than
the latter at similar phases. Spectral modeling suggests that SN 2011hr has the
IMEs of $\sim$\,0.07 M$_{\sun}$ in the outer ejecta, which is much lower than
the typical value of normal SNe Ia (i.e., 0.3 -- 0.4 M$_{\sun}$) and is also
lower than the value of SN 1991T (i.e., $\sim$\,0.18 M$_{\sun}$). These results
indicate that SN 2011hr may arise from a Chandrasekhar-mass white dwarf
progenitor that experienced a more efficient burning process in the explosion.
Nevertheless, it is still possible that SN 2011hr may serve as a transitional
object connecting the SN 1991T-like SNe Ia with the superluminous subclass like
SN 2007if given that the latter also shows very weak IMEs at all phases.
