That's not bad MPG for an Armada, especially with said hefty load of beer, booze, 4 skiers and all the gear. A 28 gallon fuel tank would get you about 420 miles for about 100 bucks, so only 25 bucks per person. Completely doable.
Wouldn't be able haul all that as well in a Prius for sure! Would need to add a Ski rack and a small trailer for the vast quantities of liquid refreshments! Or maybe a second Prius.
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I haven't skied Whiteface in quite a few years... great mountain. Gotta get out there soon.