Yes, that was a great film that I saw at the cinema in full widescreen, panovision, format in about 1968. It was a film that showed how dangerous racing at that level was, and it being all about money, satisfying the weird desire of fans to see fantastic accidents and death, and not about any safety consideration. Drivers like Jackie Stewart were starting their drive to make it a far safer sport and looking back now I wonder if this was really a propaganda film for that message, which thankfully was eventually taken on board.
The film used the panovision format to full effect in its use of the multi-split screen presentation during some of the film, with multi- images of cars going in different directions all over the screen. A great effect, which I believe MAY have been used for the first time, but I stand to be corrected by film buffs! This effect was also used to even produce better results in the 1968 film "Battle of Britain", which I saw in the West End in 1969.
Loved both of the films, and still watch the BofB every so often on DVD, which though has never the same effect as watching it in wide screen cinema format