If you want to capture all of the HVT's alive, you must first turn off the autosave. This is done because everytime an HVT is killed, the game automatically saves, to avoid having to start all over turn off the autosave. Second, before you go for an HVT, make sure you save so you can load, if the HVT is killed immediately quit and re-load your game. Third, after you capture an HVT, save immediately so you can pick right back up where you left off.
If your running low on vehicle health or ammunition, walk into any outpost on the map, and then walk back out. Once you find your car it will be fully healed and your weapons will be refilled with ammunition.
Some units of transport are hard and some aren't and here is what is hard first of all the chinese tanks they are probably the hardest to get into, the other one which is a helicopter is the VZ's helicopter the one with missiles, anti air missiles, and machine guns plus it's probably the most armoured and biggest two very hard but completeable. The rest are easy or needed a little practice on.
My fellow gamers if you ever are haveing trouble beating the missions after you beat the one were you test drive the monster truck/car for your new mechanic eva use the quarry mine place you tested it on as a training ground it works good lots of freedom to get out of a fire fight quick if nedded it's a great place to get the hang of it all from jackin tanks to dealing with rpg happy soldeirs and taking on mounted machine guns and grenade launchers trust me that place will save your life later on thanks to your training man