The first is the Explosively Formed Penetrator (EFP) is not the same IED he described in the Off-route section. The EFP is formed by the Miznay-Chardin effect, not the Munroe effect. The EFP (Miznay-Chardin) is a solid slug or can be fragmented by various means, but is not a molten jet of metal (Munroe). The Munroe effect, or shaped charge, works best in contact situations (it is the kill mechanism by which the RPG works), where the warhead contacts the target. At distance, it often turns into what has been termed as an "incoherent spray," where the jet breaks up before it strikes the target. This effect is so pronounced that vehicles in Afghanistan use cages to break up the spray inches from the armor, for those occasions where the warhead isn't damaged to the point of malfunctioning. Miznay-Chardin charges use a shallow plate to form the slug, which is not molten, and lance thru armor. These devices are generally only defeated by more armor or reactive armor.
Second, a vehicle-borne IED doesn't have to be so large as to affect the suspension of a vehicle to the point of noticing it. In places like Iraq and Afghanistan, the maintenance done on automobiles is spotty at best, and is generally only done to the point of keeping the vehicle running. Putting decent shocks in a vehicle is often a pipe dream. A charge of 200 pounds (about the weight of a person) will generally not affect the ride or stationary characteristics of a vehicle to the point of being noticeable, yet is a large enough charge to do plenty of damage.