2024 vs 2025 Tremor MPG

Hi all, took my first step towards ownership today. My local dealership has both a 2024 Tremor XLT and a 2025 Tremor available. Drove both, they feel very similar in performance. However, there is a noticeable difference in the EPA rated fuel economy - 21/27/23 mpg combined on the 2025 and 20/24/21 mpg on the 2024. This blew me away! To add to my confusion, the standard XLT AWD EcoBoost is very similar between both years - 22/30/25 mpg for the 2025 and 22/29/25 for the 2024.

Any insight into why there is such a big difference? It seems bizarre that there would be such a difference between two nearly identical vehicles, can this really be attributed to things like differences between the tires? I assume they are both on A/T tires, or am I wrong there?

One more thing, has anyone put more fuel-efficient tires on their Tremor and seen a significant improvement in MPG? Granted, things like the suspension and lift also have some impact, but I wonder if I could put a more efficient set of tires on to daily it, and keep the A/T tires on another set of rims for when needed.

Thanks in advance!