i think something needs to be asked here - since when does fuel actually EXPLODE? catch on fire, maybe, but even a damn fuel truck won't blow if you open up at one with rifles. something explosive like C4 or a rocket, yeah, it'll go up in a nice fireball, but even that dosen't do much damage to stuff around it.
with straight bullets, you'll be lucky if a fuel truck catches on fire in the first place, let alone disappear with any vehicle in it's vicinity. more likely you'll get a truck full of holes leaking liquid everywhere.
i think some have put their faith a little too much in hollywood.
if anything, the only thing that should keep the damage radius it currently has is the ammo truck. having an un-armored vehicle filled to the gills with high explosive? you'd better believe that thing it gonna anniliate a convoy when it goes up.
tanks... one of two things i think needs to happen. either they blow themselves into little fragments (which i know things like the javelin can 'encourage' ) when 100% dead, killing everything in a wide area (like they currently do), or they keep the (one burnt/rusted) model and they scale down the damage radius.. yeah, they carry ammo, but don't forget they are encased within inches of armor plating. if the armor stays in one piece, i doubt fatal blast forces are going to be subjected to everything in a 30 meter radius. heck, even the M1A1 was designed to have it's ammo storage detonate and not kill the crew.