ReviewPlayright 1989 but copyright 2010 suggests that the tracks date from 1989 when Hallyday was 46. Nine of the ten tracks are hard rockin' numbers, and the brief "Testament D'un Poète" is a romantic ballad with orchestral backing.
The title track seems to have a different, or an additional bassist: Phil Soussan may have been bassist on this set, but the fretless bass on Cadillac sounds so like Pino Palladino.
The live version from a concert at Bercy in 1990 shows the bassist for a full second at 4:22, and he looks so like Palladino to me, while the brief appearance suggests there were contractual reasons not to shown more. This live version is identical to the album track, complete with some gorgeous BGVs, so I think the entire set was recorded live.
The typical hard rock style can be heard on Possible En Moto, complete with instrumental motorcycle effect, Yves Sanna is credited as drummer for the set:
"Si J'étais Moi" is a powerful ballad, and the duet seems to be with Vanessa Paradis, who by then would be 27:
The orchestra on (Le) Testament D'un Poète was apparently the Symphonic Orchestra of Europe, conducted by Olivier Holt:
Altogether a powerful and emotional set with Hallyday at his very best,