Yea, they did even back then, try to build many cars on the same chassis. Monte Carlo, Impala, Cadillac.
My Buick was pretty fast though. Olds 455 V8, Rochester 4 barrel. 3 Tons of steel slightly faster than a school bus. Better paint for the first 10 years too. Couldn't pass a gas station though.
Remember those Lincoln Town cars that were the same length as a Princess Cruise liner? Still see those some times.
Went from Burnaby to Lion's Bay and cruised all day on Howe Sound in a buddy's cabin cruiser. Got back and it cost more to top up the friend's Lincoln than it did the boat.
Took my Kei truck to Prince George & back took almost 3/4 tank. $15.00...
next day a customer in an F350 4X4 came in and complained he could buy a part for $5 less in Prince George. At today's gas prices that trip is over $65 in my Wrangler. Gas is only $1.70 around here.