I have a HEV Limited Tucson now with 2500 miles on it. My mileage has definitely improved as I have accumulated miles. In the first 1000 miles, the mpg posted by the car was all over the place but often below 30. I tracked each fill up and I was only getting 28 - 29 mpg on a tank of gas. Not very happy. My last two tanks of gas are 32 and 33 mpg. I have had some longer drives where the displayed mpg is in the high 30's for 50 - 100 mile trips (highway but under 70 mph average). So everyone that is saying "it is the cold and break in of the car" appear to be quite correct. I'll have some more interstate driving comparisons in a week or two. Also, short trips in cold weather wreck mileage on all cars. I checked with two friends who have RAV4 hybrids and they both note a significant drop in in mileage in the winter.
I never expected to really hit the full EPA estimates for this car (I don't on any SUV I have owned). If you look at fuelly.com (2022 Hyundai Tucson MPG - Actual MPG from 56 2022 Hyundai Tucson owners
) and you can see what a bunch of people are really getting per tank of gas with this (or any other car). I looked at this before I bought the car and decided I was going to accept 5 mpg less than the RAV4 because I liked this car a lot more than the RAV4. Note that you have to ignore PHEVs when looking at fuelly.com because the site does not track electricity usage so it make PHEVs look insanely good.
One last point is that the difference between 20 and 30 mpg is much more significant that the difference between 30 and 40 mpg. So moving from my mini van to my hybrid Tucson is helping a lot more than additional improvements I could have gotten with the RAV4 or Ford Escape.
20 mpg = 5 gal/100 miles.
30 mpg = 3.33 gal/100 miles (saves me 1.67 gal/100 miles)
40 mpg = 2.5 gal/100 miles (saves me an additional 0.83 gal/100 miles)
I wish I could make my car show gal/100 miles instead of mpg because it is a much more representative metric.