It's not just the extra MPGs
It's not just the extra MPGs that is the attraction. As an owner of 2 Camry Hybrids (2012 & 2014) both of which I drove before passing onto my kids, and a RAV4 Hybrid (2017, before the growth in sales), there are other benefits.
Huge torque when starting from a red light (electric motors have high torque at 0 RPM), lighter brake usage (due to regenerative braking) - none of our hybrids have needed any brake maintenance yet, a highly reliable engine/transmission (Hybrid Synergy Drive) which has been refined over the years, quieter running when in neighborhoods and enclosed spaces (e.g. my RAV4 often automatically switches to electric-only mode in the last half mile of my commute either into an indoor parking lot at work or my neighbors streets, and finally my garage, at home). Plus with the emphasis on MPG in the dashboard, I and my family are more inclined to drive gently, and thus receive less speeding tickets!