*sigh*
Same problem in WWIIOL, take a FlaK 36 and shoot a panhard with AP, and odds are that it'll keep driving if you don't hit a crew member or other vitals. Use HE, and the concussion will mash the crew members and destroy vital components (tires, fuel,etc...)
Thin armor (BMP frontal ~25mm or something like that) will allow high velocity penetrators to pass through with minimal spalling, as there is little armor to spall.