When trying to help with airship stuff over on the old forums, I put down some (lengthy) ideas for chase rules. The first part is definitions, chasing, then racing. There were some ideas for long distance pursuit, but I cut them for this discussion.
Stats related to moving and speed.
Movement: Vehicles, whether pulled by animals or fly from True Air and the collective will of it's crew, have a Movement stat. This represents their motion inside combat and directly relates to the same stat on creatures and Namegivers. The Movement for an average airship is 0 (Flying 18). Compare that to a horse at 16 and a Common Great Dragon has 16 (Flying 24).
Cruising Speed: Only Vehicles have this stat, which are anything that requires something other than an animal (e.g.: crewed ships, such as T'Skrang riverboats, airships, and seagoing vessels, but not normal wagon or a horse-drawn boat). This stat represents the ability of some vehicles to travel at a constant speed so long as things are going well and everyone makes their rolls. It directly translates into the Overland Speed of a vehicle and is 3 times the Movement, so an airship has a Cruising Speed of 54 (yards per 6-second round). This translates to 294 miles in a 16 hour trip. Close enough to match the Travel Rate Table of 300 miles.
Chase Speed: This is 4 times the movement and is the extra effort of trying to pursue someone. An average airship has a Chase Speed of 72 while a Human can go 48 and a Common Great Dragon is at 64 (Flying 96). This is used in all of the Chase and Pursuit rules.
Overland Speed: Since I mentioned this earlier, I'll fill in the details. This is the average speed of overland travel as calculated from the Travel Rate Table on page 126 of the GMG. I'm not going to bother doing the math here, but realize that it's not always the Cruising Speed from above due to animals needing to rest more than a crew taking shifts. For example, a Namegiver on foot can go 30 miles in 8 hours. That's a movement of 9.2 yards per round.
Tracking, Shadowing, Pursuit & Chase Rules
Tracking
Tracking using the rules for Tracking as given for the Talent description on page 175 of the PG, or some similar skill or Talent as appropriate. Probably should default to Perception. I would think the Tracking Talent might even allow people to track boats on the water or ships in the air. I'll let better people figure that out, especially since it's not directly relevant. I just bring it up to spark ideas. Regardless, I mention Tracking because sometimes you have to find someone before you can follow them. Basic Perception test to spot a ship off the starboard bow, or wherever (note: horizon is about 2.9 miles away for someone on the ground and 12.2 miles away if 100 feet up, such as in a crow's nest; telescopes don't change the horizon, but do make identifying the thing easier).
Shadowing
This would be a Stealthy Stride test with the followed person rolling Perception tests to notice the Adept. See the rules on page 170 in the PG. Remember that your movement rate is halved for this. I, personally, would allow you to use the Chase rules for this, but your Chase Speed would be halved, you would have penalties, and the chased person would get bonuses to spot you. While it may be odd for someone to run from "nothing", it's always possible. For example, the shadow may only be one of the pursuers.
Chase Rules
Chases are all on the scale of six-second rounds, just like normal combat. This includes Vehicles. Make Chase Tests every round and Endurance Tests every 3 rounds.
Chase Tests: Make appropriate piloting skill roll, whether that is Air Sailing, Pilot Boat, Swimming, Running (new skill, discussed below), or something else. Default is likely Dexterity. This is against a base difficulty of X (I think the base difficulty might change depending on the activity, but I'd start with a 4 for running and swimming, as that's what Swimming in Calm Water has, and maybe 10 for ships and boats, because that sounds hard to me). This number is then modified based on weather, terrain, etc. That requires too much balancing for me to bother with at this time.
Endurance Tests: Toughness (7) instead of against a 10. However, failure nets a -1 all the same. Recovery is 1 per minute of rest. Vehicle crews do not make Endurance tests!
Success and Failure: The fastest participant is trying to get 3 successes while every other slower participant wants to get 3 + 1/5 the difference in their Chase Speeds (round up). First to their goal wins, either catching up or getting away. (edit: I defined chase speed as 4x movement earlier. Probably a better way to do this.)
Possible actions: Chase Tests are considered sustained actions. However, they can be treated as a simple action for 1 round if the participant takes a +5 difficulty to the Chase Test. This means they could cast a spell or some other action (Crunch Climb or Icy Surface might come in handy).
Distance Covered: If distance covered matters, assume everyone moves at the highest Chase Speed.
Distance between participants: I'm not sure how to make this simple. I'd determine the difference in remaining successes (much like with the Race position rules below) and then multiply that by the lowest Movement (if pursuer is faster) or highest movement (if pursued is faster). Not fully thought out, I'll admit.
Running skill: Rank + TOU step; this is training to do extended running.
Groups: if rolling for a group, use the best piloting skill and the slowest Chase Speed for figuring everything. Endurance rolls can be abstracted in this way, too, using the highest Toughness and increasing the difficulty by 1 for each participant on their side.
Racing
Racing rules are an adaptation of the Chase Rules. Instead of 3 successes, the goal is to get some higher number, depending on the length of the race. The participants all start at the same place, but position can be determined by how many successes they still need to get to win. Whichever hads the fewest successes left is winning. If two or more have the same number of successes remaining, then they are tied and probably within melee range.
Example
Two Chariots are in a race together. Chariot A is faster at a Chase Speed of 56. Chariot B is not much slower with a Chase Speed of 52. The difference is 4. Chariot A needs to get 10 successes to finish the race while Chariot B needs 11 (10 + 4/5, rounded up). After the first round, both chariots have 2 successes. This means that Chariot A has pulled slightly ahead (10 - 2 = 8) of Chariot B (11 - 2 = 9). 8 is less than 9, so Chariot A is winning.
Later in the race, Chariot A has 8 success while Chariot B has 9. They are now neck and neck, both needing only 2 successes to win. (10 - 8 = 2 vs 11 - 9 = 2). At this point, Chariot A decides to take a +5 increase to the difficulty on their Chase Test by making it a Simple Action. They use their Standard Action to stab a spear at the other Chariot. They hit, but unfortunately they do not take out the other driver, and this close to the finish this proved a bad idea.
The very next round Chariot B gets 2 successes while Chariot A gets only 1. Chariot B wins! Yay!