I read over the part of the novel depicting that scene, and I have to offer a rebuttal. Fabrizzio does indeed ask Michael if Apollonia is coming with him. To quote the passage:

"Fabrizzio stood up. His shirt was open, exposing the blue and red lines of the tattoo on his chest. 'Calo is having a cup of coffee in the kitchen,' Fabrizzio said. 'Is your wife coming with you?'"

In the novel, Michael looks upon that question as though Fabrizzio had eyes for Apollonia, though he writes it off. He indicates that she is going to her father's house, though he doesn't directly order Fabrizzio to take her there as he does in the movie.

In the movie, it seems like he makes a point of asking both if Michael is driving himself and if his wife is coming along when he's ordered to get the car. That's what got me to thinking conspiratorily, like why he would need to know if Apollonia is coming with Michael. Why should that even matter to Fabrizzio?

The novel depicts Michael watching Fabrizzio through a window, escaping through the gates, looking back over his shoulder as he did so. The movie shows Michael calling out Fabrizzio as he left. Either way, Fabrizzio knew that the car was parked away from the house (he parked it there himself), that Apollonia was in the car ready to drive up to the curb and Michael was nowhere near it. Why wouldn't he have parked it against the curb himself, so that Michael would be the one to get in and start it?

The resulting novel blast injures Michael, but wasn't enough to kill him; the movie blast causes Michael to dive into a bush, but apparently it isn't close enough to injure him. It seems to me that if he's after Michael with the car bomb, then he's better off in the pizza business. Mad bomber school didn't work out for him.

I fully admit that the theory is 'out there', as it were, but conspiratory thinking and deep analysis to the point of being off the wall sometimes is what I like about this forum.