We are worried about bringing back the mammoth (of course, while still killing everything else off) but I cant help but think a saddled up car-sized millipede could get you around town like nothing else.
Still the mental image is entertaining (but mostly horrifying).
A fiat 500 Cinquecento, at 2.97 m, already is longer (https://en.wikipedia.org/wiki/Fiat_500), and that’s a very small car, by current standards. The new Fiat 500 is 3.55 m, almost 20% longer. It’s more like a microcar (https://en.wikipedia.org/wiki/Microcar) or the electric Citroen Ami
As to weight, it indeed is lighter, much lighter. FTA: “and weighing about 50 kilograms”
..but practicality ran the horse out from that role.
Compared to your zero the millipede would have... outputs.
For example in western Europe bears were hunted to extinction before the middle ages, but you can still find bears in Russia and in the US.
I miss the flintstones cartoons from when I was a child.