Illustrated by Richard Arbib in 1972, this enormous "leisure-mobile" of the future was called the GM Bonanza. It looks like it wouldn't have done very well during the 1970's oil crisis. Or at any time when fuel is more than $.03 per gallon, really. [Image scanned from the 2006 book Driving Through Futures Past.]
It's Probably Good GM's Gas-Guzzling "Leisure-Mobile" Never Got Made