>I've been waiting for someone else to step in with British
>pronunciation, in which the [h] is *never* sounded: we tend to think
>that the American pronunciation is utterly laughable, and hic{k}-ish!
>So Chamber's allows of no other pronunciation than [vi'Ikl-], although
>most people I know tend to pronounce it as I do, namely [viakl-]
>(hope I've got that right: the first part sounds like the word "veer",
>without the "r").

I pronounce it /vi'y@k@l/, usually with a syllabic final /l/, and *no*
/h/ at all, ever. (For the record, I speak general midwestern US English
(born(1942)/raised DeKalb IL, 100km W of Chicago))  So do almost all
people in the US that I know, in normal contexts.  But what *is* a
normal context for the use of 'vehicle'?

'Vehicle' is a formal word, and is more at home in writing than in
speech, in the text of a legal prescription than in the mouth or ear
of the average citizen.  So, what are the situations in which we are
likely to hear the word (and thus learn how it is pronounced)?  Well,
one interesting one is the "legal recitation" type of conversation,
where a particular (one presumes more than usually magical) phrase
must be spoken to invoke some standard, or law, or other.

In rituals like "mirandizing" an arrested person [US idiom], a set
list has to be read out.  "You have the right to remain silent..."
Etc. If the magical effectiveness of a word stems from its written
nature, all of its letters must somehow be magical, and it's quite
common for silent letters to be pronounced under these circumstances;
cf "often".

But it's not only in ritual situations where you get it; police,
lawyers, and other court officials often use legal phraseology to
distance themselves; when they'd ordinarily ask their colleague where
they'd parked their car, they might ask someone in an official
capacity where they parked their vehicle.  Just that little extra
touch to let us know they're official. :-)

So... the hypothesis is that one contributing factor to the range of
variant pronunciations of 'vehicle' is that many of us acquire some
sense of how others pronounce it in situations where it is unduly
influenced by spelling pronunciation, recitation, and that peculiar
effect on stress, and consequently vowel quality, that comes from the
sing-song style of those condemned to say the same thing over and over:

  "Please return your seatbacks TO their upright position."

 -John Lawler                     More grammar
  Linguistics Program   University of Michigan
 "..and, who knows? Maybe the horse will sing."