I've wondered this for a long time. Chevrolet in Thailand is เชฟโรเลต, pronounced [เช็ฟ-โร-เหล็ด] chef-ro-let. Why?
The company name comes from the surname of its Swiss-French founder, Louis Chevrolet. I can't speak for the French, but in English it's pronounced shev-rol-lay (the emphasis varies between first and last syllable depending on the speaker, in my experience).
It's a classic spelling pronunciation, as with many, many foreign words borrowed into Thai, and which results in Thai pronunciations like "Robert" as โรเบิร์ต row-bert (should be รอเบิร์ต), "magic" as เมจิค may-jik (should be แมจิก), and "Amazon", as in the website, as อเมซอน a-may-zon (should be แอมาซอน). I could list a hundred more.
But there is clear precedent in Thai of French-derived loanwords inheriting the silent t. Off the top of my head I can think of three: "buffet" บุฟเฟต์ [บุฟ-เฟ่], "ballet" บัลเลต์ [บัน-เล่], and "parquet" ปาร์เกต์ [ปา-เก้]. I'm sure there are others.
Looking at the company history on the website (Thai|English), I see it only entered Thailand in 2000. Why on earth would Chevrolet Thailand choose to pronounce the "t"?
I can't imagine that is good for overall brand recognition. English has prestige in Thailand, and if Thais pronounce it the Thai way to their English-speaking counterparts, they're going to sound ignorant.
This even makes it onto the Thai Wikipedia article for คำภาษาอังกฤษที่มักอ่านผิด ("English words that tend to be mispronounced"). A big marketing FAIL, if you ask me.