Here's what's interesting: The first kanji 豊 is "toyo", which is one of the Japanese (kun) readings (as opposed to the Chinese "on" readings). But the second kanji is 田 "ta". It becomes "da" in the name because of lenition. An English version of such a sound change is when we say "waiter" like "waider": we pronounce the "t" like a "d" before the "er". So in Japanese the same thing happens: after certain sounds, the "t" becomes a "d".
So really, the name "Toyota" is a raw pronunciation of the founder's name. And what's even more interesting is what the Washington Post found out:
Writing "Toyoda" in Japanese requires 10 brush strokes...but writing "Toyota" requires eight..."Ten" consists of two strokes crossed against each other and resembles the "plus" symbol, or even a crossroads or an uncertain path. Not a good omen for a company.And, according to the Detroit Free Press:
The number eight is considered good luck in Japan because of the way it is written: two strokes side by side, placed so that the character resembles an open mountain top.So let's compare: this is 10 in Japanese: 十 and this is 8 in Japanese: 八
In Japanese, they decided to write the company's name in katakana instead of kanji, so "Toyoda" looks like トヨダ (10 strokes) and "Toyota looks like トヨタ (8 strokes). They decided on the latter.
What the Free Press gets wrong, however, is saying that the hard "t" sound is "softer" than the "d" sound. Even in English, "d" is softer than "t".
Well after I wrote all this, I decided to check out the popular Language Log (where linguists post, not simple language lovers like me), and saw that they discussed the topic in way more depth, including refuting what the newspapers reported.
So here's my obvious conclusion: it's ironic that they went to all that trouble to switch from "Toyoda" to "Toyota" because Americans pronounce it "Toyoda" anyway!