That's pretty terrible. I have a 4Runner (2013) and am averaging between 18-19 MPG... and that is either city driving or highway driving in the mountains (neither of which is good on gas). An additional disadvantage is that my vehicle has Full-Time 4WD which certainly doesn't help.
With our family expanding to 5 this December, I briefly considered selling the 4Runner and buying a Tahoe/Suburban so that we could remain a one car family. Fortunately over the summer I spent most of a week driving my in-laws 2015 GMC Sierra. No way in hell I'm going to drive something that large on a regular basis. Heck, I couldn't even fit it in our garage and driving/parking in the city was hugely unfun. I always felt like my 4Runner was too big, but it felt like a sports car after getting out of the Sierra. Looks like a minivan or much smaller 3 row crossover will have to do (I'm keeping the 4 Runner and we'll make due with it alone as long as possible...already confirmed 3 car seats across will fit...barely).