BBC News Online's Magazine recently asked their (British) readers to call in with their best American accents, and all I can say is that I have new respect for British actors like Hugh Laurie of House who can convincingly sound American. (In a recent survey on BBC's Radio Times, voters named Laurie's American accent the best trans-Atlantic imitation on television, with Michelle Ryan of Bionic Woman the worst. However, Laurie was also voted as the fourth-worst accent, which might simply indicate the paucity of British actors on American TV who are prominent enough for people to have an opinion about.)
The article is accompanied by audio selections of Magazine readers trying to pull off American accents, as well as a clip of British voiceover artist Stuart Smith giving some dialectal approximations of the sentence, "Lucky Lily liked to live in Louisiana." You can listen and form your own judgments, but what struck me about both the amateur and professional efforts was a pervasive hyper-rhoticity, or over-/r/-fulness.
The first speaker in the audio clip is Fiona Cooper of Liverpool and Suffolk, a foreign language teacher, reading a passage from Alexander McCall Smith's The Company Of Cheerful Ladies. In the line, "It was not true that such a thing could not have happened in the old Botswana," Ms. Cooper's pronunciation of the final vowel of "Botswana" as [-ər] sticks out like a sore thumb to my American ears. (Her other vowels are a bit all over the map too.) But she shouldn't feel too bad, since the professional, Stuart Smith, uses [-ər] at the end of "Louisiana" in the first two quasi-dialects he offers.
Since Smith doesn't use the "Louisianer" pronunciation in all of his American-esque voices (including impersonations of Christopher Walken and Al Pacino), I assume he's trying to simulate varying levels of rhoticity in different regional accents. That's all well and good, except that even the most /r/-ful speakers in the contemporary United States would be unlikely to render a word-final schwa as [-ər], as in "Botswaner" or "Louisianer." It is, however, typical of non-rhotic speakers' attempts at approximating rhotic accents. Perhaps most famously, when the Beatles covered "Till There Was You" (a song from "The Music Man"), Paul McCartney sang, "There were birds in the sky / but I never sawr them winging." Peter Trudgill discussed McCartney's hyper-rhotic pronunciation in this song in "Acts of Conflicting Identity: The Sociolinguistics of British Pop-Song Pronunciation" (in On Dialect, Blackwell, 1983). For further discussion, see these posts (and the accompanying comments) on the sadly defunct "Positive Anymore" blog: "Don't Believe The 'ype" and "Trudgill on Pop Song Pronunciation."
Some Americans do pronounce word-final schwa as [-ər], but those tend to be non-rhotic speakers who have what's known as "intrusive /r/." Crucially, however, intrusive /r/ only occurs before a following vowel, and not before a pause as is the case with the "Botswaner" and "Louisianer" examples (or before a consonant as in McCartney's "sawr them"). John F. Kennedy famously had a non-rhotic accent with intrusive /r/, but that feature has often been over-extended by Kennedy impersonators as if he used it in all contexts, rather than just prevocalically. The evidence on Kennedy's intrusive /r/ is clear, though. Take a listen to his address on the Cuban Missile Crisis on October 22, 1962 here. Kennedy does indeed pronounce "Cuba" as [kjubər] on three occasions in the speech, but all three occur before a vowel:
…Soviet assistance to Cuba[r], and I quote…
…any nuclear missile launched from Cuba[r] against any nation…
…which has turned Cuba[r] against your friends and neighbors…
Kennedy pronounces all other instances of "Cuba" in the speech as [kjubə]. (Interestingly, there are some places where I expected to hear the [r] liaison, but Kennedy managed to insert a pause after "Cuba" even when it wasn't prosodically necessary. It's possible that his aides made him aware of his intrusive /r/ and trained him to avoid using it after "Cuba.")
The only time I've ever heard an American with a hyper-rhotic extension of intrusive /r/ (what Ben Sadock has called "intrusive intrusive /r/") is in cases where speakers of a non-rhotic background are shifting to a new rhotic prestige model. A rather amazing example of such hyper-rhoticity is Norman Siegel, a civil rights attorney and housing advocate from Brooklyn. In this interview with Siegel on WNYC, you can hear him use [-ər] for words like "America," "arena," "Columbia," and "Scalia," extended beyond the usual prevocalic context for intrusive /r/. He adds /r/ to these schwa-ending words before pauses and consonants as well — even within a word in the case of "arena[r]s." In a sense, Siegel is trying to "pass" as rhotic, though there are glimpses of his non-rhotic background in places (as in his pronunciation of "neighborhood").
Hyper-rhotics such as Siegel are currently quite rare in the U.S., however, and I doubt that Fiona Cooper and Stuart Smith had such speakers in mind when they said "Botswaner" and "Louisianer." Rather, it's a type of imitative hypercorrection that pervades attempted traversals across the non-rhotic/rhotic divide. And it apparently takes an ear as keen as Hugh Laurie's to avoid it.