I've been browsing want/for sale ads in Ebay for various car-related paraphenilia, and two models that seem to get messed up a lot are:

Le Sabre (Buick)
Fireflite (De Soto)

which are often seen as:

Le SabER or LA Sabre (or both )
FireFLIGHT

I know there are more, so I thought it would be fun to let everyone release their biggest pet peeves!

Oh, and don't worry about your non-automotive spelling here. All is forgiven!

I know of a couple more Gran/Grand ones. I have a book that has a Ford Gran Torino picured with "Buick Gran Torino" in the caption!

Chevy Camero instead of Camaro

Volkswagon instead of Volkswagen, this error is commited a lot by the americans.

I often forget the "s" when I write Volkswagen, but it is a typo rather than a lack of knowledge

A very common error is in VW Scirocco: you can see it written in so many ways... Sciroco, Sirroco, Sirocco, Scirroco, etc.

A favourite in our local evening paper is ‘Citreon’. I’m never sure whether it’s due to the advertiser not being able to spell the name of his car or some dimwit in the newspaper office.

Lotus Esprit seen many times writen as Spirit or Espirit.

I do not remember having seen that error

This makes me think to another one: "e" added in front of a name beginning by "sp", which seems to be a typical Spanish error (as the words like "Special" become "Especial" in Spanish, and no word begins by "sp" in that language if I am correct)

You have not seen it ever? its really common, and yes, we dont have any words beginning by "S" to make this sounds we need an "E".

Here in Finland the German Opel names is often spelled in English.
For example Opel Cadet (Kadett) or Record (Rekord)

Record is even a common misspelling over here in Germany. Seantor instead of the Senator is also seen quite often.

I can´t count all the innumerable mutations of "Cadillac" which I have seen through the years. Be sure: Everything is allowed and I´ve seen it spelled by up to eleven (!) characters.

Here´s the most official Cadillac-misspelling-generator, which allows you to create such neat disfigurements like Cadilac, Caddillac, Cadylack or everything else you could ever imagine :

1. C
2. A or E or Ä
3. D or DD
4. I or Y or even IE
5. L or LL
6. A or E or Ä
7. C
8. + an optional K