The Tesla Model X electric crossover has been delayed multiple times, but Tesla Motors appears to have committed to delivering the first examples before the end of the year.
Increased numbers of sightings of camouflaged prototypes testing in public could be good sign that Tesla will meet its deadline.
And while the carmaker would probably prefer less attention, Model X spotting can also reveal more details about the vehicle.
Two recently-posted spy videos may do just that, according to Autoblog.
The first video shows a dirty Model X prototype being towed on a trailer.
Since the Model X is an all-wheel drive utility vehicle, the implication here is that Tesla was testing the vehicle off road.
Tesla Model X prototype on Arizona road, July 2015 [by YouTube user count783]
It's hard to imagine a vehicle getting such a thorough coating of grime any other way, although it would probably be unlikely that the Model X was tackling rocky trails or a desert rally stage.
Given its apparent low ground clearance, and underpinnings at least somewhat related to the Model S sedan, the Model X most likely won't be a serious off-road vehicle a la Jeep Wrangler.
The second video--unfortunately shot entirely in portrait layout--actually shows a Model X driving in traffic with unusual sensors attached to the exterior.
Two round objects are fixed near the car's passenger-side front wheel well, with wires running between them.
It's unclear what these devices are for, although Autoblog speculates they may have something to with Tesla's "autopilot" autonomous-driving system.
Tesla Model X prototype in Culver City, California [photo by Instagram user jmtibs]
The autopilot systems is expected to launch soon in limited form on the Model S, although Tesla hasn't set a firm launch date.
Cars equipped with the system's hardware have been rolling off the assembly line for several months, and CEO Elon Musk has said he is testing the software during daily commutes.
During a finance conference call last month, Musk said Tesla planned to begin Model X deliveries in three to four months.
The company has used the past few months for additional development work, which Musk has said is necessary to iron out any potential issues.