No - what it means is that it takes 20 energy units to cruise.
Your guns take like 20 a shot from the power source, and you can run out if you have too high guns (see specials at 240+ per shot) and you shoot for too long.
The cruise engines also need energy to work, just like a weapon. That is what the number means. Stick that number above the charge rate of your fighters power supply and you will soon come out of cruise. This is how my 2nd hand ships are made to be bad (well - one of the ways) is that their engines slowly drain power out (ie, the drain rate at cruise is slightly higher than charge rate) so that it drains the power, you lose your cruise and its a pain, but what do you expect from cheap second hand ships??
Next - thrusters power comes from a different source as well. Same power unit, two power supplies.
Here are two powerplants
[Power
nickname = ge_fighter_power01
ids_name = 263705
ids_info = 264705
volume = 0.000000
mass = 10
DA_archetype = equipment\models\hardware\li_fusion_reactor.3db
material_library = equipment\models\hardware.mat
capacity = 1000
charge_rate = 95
thrust_capacity = 1000
thrust_charge_rate = 100
lootable = false
[Power
nickname = ge_fighter6_power01
ids_name = 263709
ids_info = 264709
volume = 0.000000
mass = 10
DA_archetype = equipment\models\hardware\li_fusion_reactor.3db
material_library = equipment\models\hardware.mat
capacity = 10400
charge_rate = 1040
thrust_capacity = 1000
thrust_charge_rate = 100
lootable = false
These are starflier and eagle respectively
Notice parts in bold? Those are the two different power supplies. Now - as you can see the eagle has substantially more power supply than the starflier for weapons, but the same for thrusters. This is to make sure that they both remain balanced by having the same thrust time. Increasing the thrust recharge to over 165 (which is the thrust drain on the worst thruster) will mean you have unlimited thrust supply. Weapons and engine come off of the other supply - so note that you would need MORE drain on an eagles cruise to make it stop (not capactiy - just drain). Whereas 97would bring a starflier to a standstill in due time (a long time) you would need over 1040 for the eagle. Hope that helps
Chips