Brazilian Portuguese
The assertion that that the /rr/ in "carro" is normally pronounced as h, x or χ is simply wrong. To the extent that such pronunciations exist at all, they are restricted to certain regions and, by and large, to uneducated speakers, and thus fall far short of being considered standard. As a matter of fact, they sound rather odd to most native speakers and would hardly ever be encountered in the media. Without conducting a scientific survey, I would say that x and χ for initial /r/ and intervocalic /rr/ are restricted to poorly educated speakers from the city of Rio de Janeiro and its surroundings, while the media and all reasonably educated speakers there are actually notorious for their use of [ʁ]. Analogously, [h] confines itself to the Centro Oeste, a large but sparsely populated region, and, again, to uneducated speakers.