In order to get a meaningful reduction in consumption, you need to be driving a sedan or coupe.
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Many of the bigger vehicles have unnecessarily large engines. However, that's not necessarily true across the board.
With the Golf Sportwagen (EU name Golf Variant) off the market in North America now, it leaves Volvos and Subarus as the only option.
I predict that in the next decade, station wagons will get rediscovered as manufacturers try to maximize range and reduce battery volume as electrification marches on.
Edit: forgot about Subarus
Are they not the same class of car?
Outback "competes" with the crossovers which are usually shorter in length and have taller interior space.
I purchased a base Golf Sportwagen with 4Motion back in 2017 for around $29k which was surprisingly nicely equipped (DSG, tunable engine, decent soundsystem). A similarly equipped Suburu would have been mid-to-high $30s.
If I had freedom to "flex", I would have gone for the Volvo because of the safety street cred.
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.
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).
"Unnecessarily large engine" sure sounds like something that would have negative consequences, but Cylinder Deactivation (CDA) is a thing. Just like your CPU, your engine doesn't need to spin up every "core" if it's not loaded to 100%. And fewer concurrent explosions per second, means less gas needed to drive all those explosions. A V8 that's only driving 4 of its 8 cylinders in most situations, is likely going to be even less gas-guzzling than a V6 that always has to drive all 6 cylinders. (Well, other than the fact that the V8 has to work slightly harder to move a car that's heavier from the additional engine weight.)
Of course, not all vehicles have CDA. But more and more do.
And, relevant to the discussion — as of the 2021 model, the F-150 has CDA. (https://pickuptrucktalk.com/2020/10/2021-ford-f150-5-0l-v8-e...)
Sure, however the F-150 was by far the biggest selling vehicle at least up until 2019. Over 3 times as many sold as the second most popular vehicle.