Everybody had personal transportation vehicles which consumed cellulosic biofuel: horse and mule engines in carriages and chariots

The evidence is very much against that.

I live in an early suburb, developed in the late 1830s, 1840s and early 1850s for the uncivilized Americans. 1.1 mile to the civilized French Quarter, 1 mile to the CBD from my home. My neighborhood (Lower Garden District) was largely upper middle class professionals and middle level merchants.

Several slave quarters remain but evidence of only one carriage house. Taxis were occasionally used, evidenced by a number of extant marble blocks on the curb to make it easier to get aboard (they are all "middle of the block" where they are left, so I assume common use by all).

The Garden District (two blocks away) was the home of millionaires (in 1840s gold & silver dollars). Carriage houses were much more prevalent but still in a minority.
Some may have been lost in the last 100 years, but I am confident that more than half OF THE MILLIONAIRES never had personal horses in New Orleans.

Instead they rode the St. Charles, Prytania and Magazine streetcars and shopped locally.

Best Hopes for more Urban Rail,

Alan