I'm starting with the assumption that a round is about a minute long.
My problem: The range bands just seem way too large in-atmosphere, and I think it allows vehicles to move far too quickly, especially the big slow ones (hint: AT-ATs moving at 3,600 mph [5,800 kph] with 2 Move Maneuvers in a round. That's almost halfway around the earth in an hour*).
My goal is to propose as few house rules as possible (though there may be a couple tweaks), I mostly just want to change how large the range bands on a planet are.
*I didn't realize just how bad it was until I calculated it out.
First, here's my interpretation of the distances as per RAW.
Close: 0-5 miles (0-8 km)
Short: 6-31 miles (9-50 km)
Medium: 32-62 miles (51-100 km)
Long: 63-124 miles (101-200 km)
Extreme: 125+ miles (201+ km)
Secondly, here's an approximation of the speeds for speed 1-3 on the ground, with the current range bands (using Close to Medium since it takes all of them 2 Maneuvers to go from Long to Extreme, which comes out to almost 5 times the speed of sound).
Speed 1: 480 mph (768 kph)
Speed 2: 660 mph (1,056 kph)
Speed 3: Same as speed two
Now the proposed fix:
First off, I suggest limiting sil 3 ground vehicles to 1 Move Maneuver (though they can still take 2 Maneuvers [equivalent to the Ponderous species ability]), and sil 4+ ground vehicles to 1 Pilot Only Maneuver (equivalent to sil 5+ ships).
Secondly, here's a revised speed chart for in-atmosphere:
Speed 1: 1 Maneuver to move within Close range, 3 Maneuvers to move between Medium and Long range, 4 to move between Long and Extreme.
Speed 2: 1 Maneuver to move between Close and Short, 3 Maneuvers to move between Long and Extreme.
Speed 3-4: 1 Maneuver to move between Close and Short or between Short and Medium.
Speed 5-6: 1 Maneuver to move between Close and Medium, 2 Maneuvers to move between Close and Long, 1 Maneuver to move from Long to Extreme.
Thirdly, here's a chart of what I think are the actual speeds of the different Speeds are supposed to be, in miles/kilometers per hour, and miles/kilometers per minute (the more relevant of the two).
Speed 1 speed: 0-30 mph (0-50 kph)
Speed 1 speed: 0-0.5 mpm (0-0.8 kpm)
Speed 2 speed: 30-75 mph (50-120 kph)
Speed 2 speed: 0.5-1.25 mpm (0.8-2 kpm)
Speed 3-4 speed: 75-300 mph (120-500 kph)
Speed 3-4 speed: 1.25-5 mpm (2-8 kpm)
Speed 5-6 speed: 300+ mph (500+ kph)
Speed 5-6 speed: 5+ mpm (8+ kpm)
Finally, here's a revised distance chart for in-atmosphere:
Close: Out to just over half a mile (about 1 kilometer)
Short: From just over half a mile to about 2 miles (1-3 kilometers)
Medium: 2-6 miles (3-10 kilometers)
Long: 6-10 miles (10-16 kilometers)
Extreme: 10+ miles (16 kilometers)
Without encumbering the system too much, while still covering all the bases, it necessitated actually speeding up the lower speeds a little bit, and in some cases slowing down the faster speeds to make them all fit with the other speeds. Because of that, here is a second speed chart that shows the actual actual speeds of the different Speeds in miles/kilometers per hour, and miles/kilometers per minute (the more relevant of the two). I'm basing this off of Close-Medium and Medium-Extreme. The first category is, in my opinion, the more important as you are not going to deal with Medium-Extreme distances as much. As you can see, the slower speeds are faster over the longer distances and the faster speeds are slower over the short distances.
Close-Medium:
Speed 1 speed: 30 mph (50 kph) (with 2 Move Maneuvers, 60 mph [100 kph])
Speed 1 speed: 0.5 mpm (0.8 kpm) (with 2 Move Maneuvers, 1 mpm [1.6 kpm])
Speed 2 speed: 36 mph (60 kph) (with 2 Move Maneuvers, 72 mph [120 kph])
Speed 2 speed: 0.6 mpm (1 kpm) (with 2 Move Maneuvers, 1.2 mpm [2 kph])
Speed 3-4 speed: 60 mph (100 kph) (with 2 Move Maneuvers, 120 mph [200 kph])
Speed 3-4 speed: 1 mpm (1.6 kpm) (with 2 Move Maneuvers, 2 mpm [3.2 kpm])
Speed 5-6 speed: 120 mph (200 kph) (with 2 Move Maneuvers, 240 mph [400 kph])
Speed 5-6 speed: 2 mpm (3.2 kpm) (with 2 Move Maneuvers, 4 mpm [6.4 kpm])
With 1 Move Maneuver, the first two are within the range, but the faster ones are disadvantaged, moving slower than the target.
With 2 Move Maneuvers, all of them fit within the range I provided as a target, with the exception of Speed 1. However, most of the vehicles bound to Speed 1 maximum would be limited to 1 Move Maneuver, and smaller, usually faster, vehicles going at Speed 1 would not generally be bound to Speed 1, allowing them an in-between speed if they take the system strain.
Medium-Extreme:
Speed 1 speed: 68 mph (110 kph) (with 2 Move Maneuvers, 136 mph [220 kph])
Speed 1 speed: 1.14 mpm (1.8 kpm) (with 2 Move Maneuvers, 2.28 mpm [3.6 kpm)
Speed 2 speed: 96 mph (155 kph) (with 2 Move Maneuvers, 192 mph [310 kph])
Speed 2 speed: 1.6 mpm (2.5 kpm) (with 2 Move Maneuvers, 3.2 mpm [5 kph])
Speed 3-4 speed: 120 mph (192 kph) (with 2 Move Maneuvers, 240 mph [384 kph])
Speed 3-4 speed: 2 mpm (3.2 kpm) (with 2 Move Maneuvers, 4 mpm [6.4 kpm])
Speed 5-6 speed: 210 mph (336 kph) (with 2 Move Maneuvers, 420 mph [672 kph])
Speed 5-6 speed: 3.5 mpm (5.6 kpm) (with 2 Move Maneuvers, 7 mpm [11.2 kpm])
With 1 Move Maneuver, the first two are definitely too fast, but the last one is too slow.
With 2 Move Maneuvers, the first two are definitely way too fast, but the last two fit neatly into their sections.
I’m definitely open to suggestions on improving this (or obvious stuff I missed), but I tried to make it as close to RAW and as simple as possible. Here is a list of the relevant changes that you need to play with this:
I classify Ground Vehicles as anything that has to maintain physical contact with the ground, or has a maximum altitude of 100 meters or less.
1. New limits on Silhouette and Maneuvers:
Silhouette 3 Ground Vehicles: May only take 1 Drive Maneuver per round, but may still take 2 Pilot Only Maneuvers if the proper conditions are met.
Silhouette 4 Ground Vehicles: May only take 1 Pilot Only Maneuver per round.
2. Range Band Distance Chart:
Close: Out to just over half a mile (about 1 kilometer)
Short: From just over half a mile to about 2 miles (1-3 kilometers)
Medium: 2-6 miles (3-10 kilometers)
Long: 6-10 miles (10-16 kilometers)
Extreme: 10+ miles (16+ kilometers)
3. Drive Maneuver Speed Chart
Speed 1: 1 Maneuver to move within Close range, 3 Maneuvers to move between Medium and Long range, 4 to move between Long and Extreme.
Speed 2: 1 Maneuver to move between Close and Short, 3 Maneuvers to move between Long and Extreme.
Speed 3-4: 1 Maneuver to move between Close and Short or between Short and Medium.
Speed 5-6: 1 Maneuver to move between Close and Medium, 2 Maneuvers to move between Close and Long, 1 Maneuver to move from Long to Extreme.