Part of me doesn't really mind these one-at-a-time releases. It gives me plenty of opportunity to use one vehicle before the next one is released, which I then again can dedicate up to a week to, and so on and so forth.
The other part of me does mind, partly because it takes so long for all vehicles to be released, partly because they'll likely be released in the way that generates the most Shark sales. With that in mind, I can see the Infernus being one of the last, in an attempt to build up the hype amongst people who aren't in the knowing and might buy a card in the inevitable bonus week leading up to its release.
Seriously, though, I think there's a connection between the amount of disappointed players hoping for it to be a Countach and how much I look forward to the Infernus. I mean, I wouldn't say no to a Countach, but I grew up thinking the Diablo SV was the ultimate in going extremely fast. There exists no universe in which I'm not putting at least one of those in my garage. Apart from our universe, that is.