Something I found on google
I know this is a bit off subject but I felt a true Brit contribution was
required! Jaguar the word is derived from the Tupi-Guarani word yaguara and
was a biologists' class-name for all carnivorous beasts, first used in
1604. Preferred pronunciation is (cover your eyes, fellow Brits) Jagwar.
Furthermore, the feline, Panther Onca originated from South America [not
Coventry, UK
]. So, as is often the case, our American cousins have got
the word and its pronunciation technically correct. However, as a car, the
word was first used by (Sir) William Lyons in 1935 in the form SS Jaguar. I
have a video tape of Lyons talking about his cars in the 1950's. He
pronounces "his" word Jag-u-ah - with a well-bred English accent so.. 'ah'
not 'ar' at the end. Since he selected the word for our beloved cars I feel
his pronunciation should stand!