I've owned this mazda6 for 2-3 months now.
Mileage is at about 1.1k.
I drive a mixture of highway and city roads.

So far my Average MPG is at 23.4 and I've watched it trickle down from 25.
I'm aware the number is going to depend on my driving habits and also the mileage I've put on the engine.

However 23.4mpg is quite off from the 28City/40Highway rating.
I don't imagine that the mpg will just get up from a few more 1000 miles. but I could be wrong.

Are these numbers to be expected or is there something wrong here?
If I contact my dealer about this they'll just tell me to put more miles on car.

 

I can't say if it's normal but I have the same results. I've only put less than half that number of miles on my 2016 Mazda6 Touring but, I get the same mpg results as you. I was also disappointed. I am coming off an older car where my average was still much lower, but, this is not the savings I expected (especially since I was coming off a 6-cyl that had some real power.)

Still, if I see 28 city on a sticker, I expect 23 city or so since I am not driving like a grandma. But right now I have an average of 24 and that is mixed city/highway driving, so, I am not really seeing where that highway mileage is kicking in.

 

I have a new 2016 cx5 gt with just over 1000 miles...took my son back to school, about 7 hours of highway miles and the average mileage actually trickled down a point or two. I was going to check w dealership, but I'm sure they will say weather is very cold, car is new and so on.