Horizon Mini-Zep has a standard operational time of 8 hours - a whopping 2 hours more than the standard operation time of a normal drone. I'm thinking that this should be at least 12 hours since I'd think that LTAV would count at least as Improved Economy.
Which, oddly enough, is not an available option for a drone unless you scrap the special drone mod rules and use the generic vehicle rules. In fact, the generic rules seem much more robust than the drone specific rules, providing a number of options that would be useful for drones - ECM, Signature Masking, Suncell, Gridlink Override (or Skylink Override, as the case may be), Nanomaintenance System, Smuggling Compartment, Touch Sensors, Extreme Environment Modification, Chameleon Coating, Smoke Projector, Road Strip Ejector, Missile Defense System, Spoof Chip, and Retrans unit.
In short, the optional drone modification rules seem like an option without perceptible benefit - they are less flexible and more cumbersome. The only things they really add are:
1. the ability to reduce stats for more mod points, which for some reason the generic rules don't provide information on even though it is expressly mentioned as a thing elsewhere (removing seats to add more storage or room for mods)
2. That drones are more space limited than vehicles, body for body, though that is debatable since they don't have to provide passenger space or amenities and typically have a lower Body as well
The second item is a non-issue in my mind, but can be remedied by simply making an exception to the generic rules that states "unlike vehicles, drones only have 1 point in each category, but they also have a number of additional points equal to their body (or indicated in parenthesis next to their body stat in the drone's stat block) that can be applied to any category", where the one point in each category represents the freebie point mentioned in the drone section.
The first is easily solved by providing some rules for doing so (perhaps with appropriate drone exception if needed). Again, I think that the exception for drones is unneeded, but maybe there is a game balance issue I am missing. The rules for removing features to gain mod points would roughly equate to the drone rules except allowing each stat to be dropped by one to gain a mod point (as opposed to only gaining the benefit from one stat as mentioned in the drone section) and the same rule for reducing body by up to half. In addition, additional features could be removed to gain mod points equal to adding them in. Seating would probably be an exception (and there may be others that might benefit from an exception where they are percentage based), but it would probably be akin to one mod point per passenger.
To be sure, both changes are rough and so might need some slight refinement to avoid abuse, but would have provided more consistency and saved about five pages leaving in the additional weapon mount sizes and rules for autosofts). Which could have been used for additional artwork, or kick ass RCC stuff, or clarification on what attributes to use for the various skills when controlling a vehicle via various methods, or explaining what the Remote Operation specialization for the piloting skills applies to, or what EW specializations apply to the various new actions provided on page 30 (and the ones included in the core book), etc.
Speaking of which, here are some of my guesses (note that some items fall into multiple areas):
Communications: Confuse Pilot, Suppress Noise, Hide, Jump Into Rigged Device, Snoop
Encryption: Check Overwatch Score, Hide, Jump Into Rigged Device, Snoop
Jamming: Suppress Noise, Hide, Jam Signals
Sensor Operations: Break Target Lock, Detect Target Lock, Target Device, Perception via Sensor Array
ETA: Add perception via Sensor to Sensor Operations spec.
Also, upon further review, it would take a lot more points to squeeze drones into the generic mod rules effectively (since it is 5 points instead of 1 for a speed upgrade, and 4 points for handling and acceleration, etc). I still think it's doable, but my rough draft above would not be sufficient. Since most drones are body 4 or less, basic modification would be difficult or impossible under the generic system even with body points per category, so I concede defeat for now while I go back to the drawing table, but I shall return!