As far as vehicle rules, there were the official GW ones (originally from Exterminatus #2), which the two part article was a later fan-made extension/errata for. That original article is here: http://www.mediafire.com/file/4mwx1amqhzd/VehicleRules.pdf
I would definitely take into account elements of the later article though (things like Ramming), as they point out some very massive holes in some of the original.
Even said (grumble powers activate) I feel the main drawback of the official rules was that vehicles were far too "explodey" (there were very dramatic effects from even minor damage).
Personally, I use an alternative damage system - one that uses high armour values to represent the relative difficulty of doing meaningful damage metal components, but a moderately low toughness, because any actual damage will usually have fairly significant effects on something like an engine;
As such, the vehicle sheet I have for my Rhino/Razorback has Toughness 60 (which is fairly high by the standard of my rules, given the Rhino is supposed to be legendarily rugged and dependable vehicle), but has a range of armour values (dependent on location and direction) between 10 and 16. As such, it's generally immune to pistol fire from the front, although things like boltguns (and to a lesser extent, Revised Armoury rifles and shotguns) can inflict minor hits.
I've also changed the damage tables to have five injury levels rather than three. Vehicles tend to be fairly wrecked by Serious injury, but it takes Crippling damage to massive explosions and the like - which means that getting into a vehicle is a bit less like voluntarily stepping on a landmine.
I have yet to actually post up my rules though, because I'm lazy and have far too many other things I'm failing to do as well...