A VERY intelligent rover

As mentioned before, two of the major issues in the Mars One involve the definition of "existing" technology and the way the project fails to account for technological unknowns and development costs. Case in point, the proposed Mars rover, which will have to greatly exceed any of its predecessors in functionality while remaining small enough to be lowered by sky crane (assuming that Mars One isn't planning on developing entirely new EDL [entry, descent and landing] technology). 

Here are some relevant passages from the Mars One website [emphasis added].

From the technology section:

Mars Landing Module: Mars One will secure the landing modules from one of the experienced suppliers in the world, for example Lockheed Martin. Similar landers will be equipped to perform different functions.

Carrying Life Support Units that generate energy, water and breathable air for the settlement.
Carrying Supply Unit with food, solar panels, spare parts and other components.
Carrying Living Units that are outfitted with deployable inflatable habitats.
Carrying Humans to the surface of Mars
Carrying Rovers to the surface of Mars

Rovers: Two rovers will be sent to Mars to set up the outpost before the humans arrive. One of them will explore the surface of Mars in search of the most suitable location for the settlement, transport of large hardware components, and the general assembly. Mars One’s rover supplier will determine the exact rover strategy; it is possible that instead of one large rover, multiple smaller rovers will be sent. For example, a main rover accompanied by a trailer system used for transporting the landing capsules.

You often encounter this kind of nonchalance about details in statements from Mars One, along with absolute confidence in the budget estimates that were based on those vague details.

The Mars One roadmap gives an idea of just how versatile the rover will have to be. Keep in mind, all of this has to be done autonomously before the first crew arrives.

One intelligent rover and one trailer will be launched. The rover can use the trailer to transport the landers to the outpost location. On Mars, the rover drives around the chosen region to find the best location for the settlement. An ideal location for the settlement needs to be far enough North for the soil to contain enough water, equatorial enough for maximum solar power, and flat enough to facilitate the construction of the settlement.

When the settlement location is determined, the rover will prepare the surface for the arrival of the cargo missions. It will also clear large areas where the solar panels will lie.
...
The six cargo units will land up to 10 km away from the outpost on Mars. The rover will pick up the first life support unit using the trailer, place the life support unit in the right place, and deploy the thin film solar panel of the life support unit. The rover will then be able to connect to the life support unit to recharge its batteries much faster than using only its own panels, which will allow it work much more efficiently.

The rover will pick up all the other cargo units and deploy the thin film solar panel of the second life support unit and the inflatable sections of the living units.
...
The rover will also deposit Martian soil on top of the inflatable sections of the habitat for radiation shielding.

We are talking about a lot of soil here (think five meters) and a lot of heavy lifting and a lot of precise work. Add to that concerns like dust and the need to be absolutely maintenance-free (if the rover breaks down, future launches can't proceed). To accomplish all of this will require a tremendous amount of engineering talent. Mars One claims this can be done quickly at bargain-basement prices.

For context, take a look at the development costs for the last big advance in the field [emphasis added]

NASA called for proposals for the rover's scientific instruments in April 2004,[80] and eight proposals were selected on December 14 of that year.[80] Testing and design of components also began in late 2004, including Aerojet's designing of a monopropellant engine with the ability to throttle from 15–100 percent thrust with a fixed propellant inlet pressure.[80]

By November 2008 most hardware and software development was complete, and testing continued.[81] At this point, cost overruns were approximately $400 million. In the attempts to meet the launch date, several instruments and a cache for samples were removed and other instruments and cameras were simplified to simplify testing and integration of the rover.[82][83] The next month, NASA delayed the launch to late 2011 because of inadequate testing time.[84][85][86] Eventually the costs for developing the rover did reach $2.47 billion, that for a rover that initially had been classified as a medium-cost mission with a maximum budget of $650 million, yet NASA still had to ask for an additional $82 million to meet the planned November launch.