Your 30 year old Roadmaster has a ginormous footprint, and holds 54.7 cu. ft. of luggage space behind the second row, and 92 cu. ft. behind the first row. They don’t quote a “behind the third row” figure, as use of the rear-facing jump seats almost entirely precluded carriage of any luggage.

For comparison, a Buick Enclave, which would be the closest equivalent vehicle in Buick’s current line-up, has 57.7 cu. ft. behind the second row, 97 cu. ft. behind the first row, and 23.6 cu. ft. behind the third row. It matches the Roadmaster’s 5,000 lb. towing capacity, if equipped with the optional towing package. With all this, the Enclave gets better EPA fuel economy than the Roadmaster; either 21 or 23 MPG EPA combined (for AWD and FWD, respectively), vs. 18 MPG combined for the RWD only Roadmaster. The Roadmaster is also short ~60 HP, at 260 HP, vs. the Enclave’s 328 HP.

The Enclave is nearly a foot shorter than the Roadmaster, despite having a five inch longer wheelbase, so I’ll grant it might have an issue with the plywood. It’s certainly also a much larger initial investment, compared to its depreciated 30 year old ancestor.