All four sound fine to my native ears. "It's going to run ..." is most natural when talking about a vehicle. (French if I recall does not distinguish "working" from "running" for machines generally.)
While the primary meaning of 'marcher' is 'to walk', it can be used for machines and vehicles indeed. 'Rouler' is for vehicles only. Interestingly in English the verb 'to run' is used, suggesting higher speed.
The expression “to work better” is quite common but I don't remember seeing “to work less well”. And as I was taught that « plus grand » translates to “taller” but « moins grand » to “not as tall as”, I expected something more involved.
Yes, I might naturally say "It's no longer going to run as smoothly." But, to me, phrasing it as "It's going to run much less smoothly" adds to the humor by suggesting that it will to _some_ degree still run "smoothly" (when in fact it won't run at all).
While the primary meaning of 'marcher' is 'to walk', it can be used for machines and vehicles indeed. 'Rouler' is for vehicles only. Interestingly in English the verb 'to run' is used, suggesting higher speed.
The expression “to work better” is quite common but I don't remember seeing “to work less well”. And as I was taught that « plus grand » translates to “taller” but « moins grand » to “not as tall as”, I expected something more involved.