One reason why SUVs are as popular as they are is that car manufacturers are allowed to produce less efficient cars if they are larger and with off-road capability. This allows bigger, less efficient cars compete with the more efficient ones because the sale price ends up being close enough to the more efficient counterparts for this to not matter.
This was true like in the 1990s. It hasn't been true in a very long time (almost 20 years now). The only limit at which these standards don't apply is truly heavy duty (5000 pounds) and not even a hummer is over that threshhold.
Edmunds has the 2004 H1 at 7,608 lbs. [0] and the 2009 H2 at 6,614 lbs. [1] 2004 and 2009 are the newest Edmunds has for those models. Looks like the new GMC Hummer EV is going to be over 9,000 lbs. [2] The lightest 2022 Chevrolet Tahoe that I could find on Edmunds was 5,473 lbs. [3]
[0] https://www.edmunds.com/hummer/h1/2004/features-specs/
[1] https://www.edmunds.com/hummer/h2/2009/features-specs/
[2] https://www.motortrend.com/news/2022-gmc-hummer-ev-pickup-ed...
[3] https://www.edmunds.com/chevrolet/tahoe/2022/features-specs/
https://www.motorbiscuit.com/why-dont-heavy-duty-trucks-have...
Now, keep in mind, I'm talking about actual fuel usage. Not "ideal testing conditions". For example, my Chevy Equinox is supposed to get 32 highway - but it really only gets 26 (cruising at 70mph with no traffic).
Certainly a lot of these lil crossovers with natural-aspirated 4-cylinder engines can really strain to heft a bigger vehicle up from a stop (I'm looking at you, Subaru!), but once one is driving hwy speeds they are really quite fuel-sipping.