How to include equipment level in planning D20 Modern encounters?

Question

Obviously equipment matters a lot in modern combat. A tank crew in a modern tank can almost always defeat men armed with only small arms. The d20 modern system does not take this into account when planning encounters; the tank crew in the tank or out of it would have the same challenge rating (CR).
In a more realistic example, an enemy with hand grenades is much more dangerous than one without. Enemies with rifles are likewise more difficult than enemies with revolvers.

How can I fairly take equipment into account when planning d20 Modern encounters?

Answer 1

Does d20 Modern have the same DM advice regarding terrain features as DnD? I mean the "if terrain provides a significant advantage to the monsters, increase the encounter level (and thus the XP reward) by at least 1 level, possibly more" suggestion. You could use that rule as a baseline for adjusting encounter levels.

A sniper hidden somewhere in a 10 story building is much more dangerous than a sniper standing in the middle of the road. A pilot is much more dangerous inside his combat helicopter than out of it - and the same applies to the tank crew.

Perhaps you could apply a flat +1 to the encounter level when a pilot is inside the appropriate vehicle, and an additional +1 to +3 depending on the vehicle's weaponry/defenses (e.g., +1 if the PCs have anti-tank weapons and the tank lacks reactive armor, or +3 if the PCs don't have anti-tank weapons and the tank has additional anti-infantry weapons).

So a tank crew inside a tank not specifically protected from the PCs would have an encounter level of CR+2, while a tank crew inside a tank specifically protected from the PCs and armed against them would be CR+4. Assuming that CR == average party level this would make for a very dangerous fight and the best idea would probably be to try to outmaneuver the tank or flee from it (I sure wouldn't want to take on a tank head on!).

Answer 2

By "fair" do you mean "know if you're going to kill your PCs" or as in "I want to give them enough XP?"

Well, the existing mechanic that is somewhat supposed to handle this is Wealth. Sure, it's unrealistic and ties wealth to character level, but if you want obsessive balance then that's the route to go.

A tank has a purchase DC of 47. "By the book," that would need to come out of one or more NPCs' Wealth and if it does, it's balanced "for free." So say 21 otherwise ill-equipped soldiers could have one tank out of their Wealth (assuming 20 of them Aid Another for a +40 on the check).