You're being rather pushy, here. I do not add R to sauce, or remove one from horse. I, like many other English speakers, just don't rhoticise the R in horse.
The British pronunciation of horse, despite some subtlety that varies across accents on the r (which is also a thing here) is not remarkable from an American ear.
Okay? I didn't say anything about being remarkable. It's just different. Rhotic accents will hit the R, while non-rhotic ones won't. I'm not sure what your problem is, here.
If it were an issue of rhoticity your horse would sound more like the American sauce, but its the other way around.
It is an issue of rhoticity. Literally the only difference is the rhotic R. I say horse like sauce because I don't rhoticise the R. This doesn't make my horse sound like an American sauce - and why would it? Why would a non-rhotic speaker pronounce a word without an R anything like a rhotic speaker's R?
