What to Expect
After applying this solution, bots should approach the building in a vehicle, exit the vehicle at the entrance, and continue to the Power Node or Core. Bots should exit their vehicle immediately instead of hovering around the entrance, and should not crash their vehicle against the entrance. In other words, they should act smoothly and produce a satisfactory result. The only drawbacks is that bots may park their vehicles at the entrance, which may hinder the path. Also, bots will only take their vehicles to one entrance of the building; they'll take the rest on foot. But I think you'll agree, this can take a map from being non-playable to playable.

This has NOT been extensively tested, and the results are not guaranteed. Some parts of this solution can probably be bent or massacred and it may still work. Any feedback from trying this would be very much appreciated.

The Solution
First of all make sure the entrance you're going to use is fully accessible by vehicles and clear of anything that may hinder bots, such as trees, meshes, etc. Next, you'll want to make sure it's pathed properly, with road path nodes outdoors, and ordinary bot path nodes indoors (You may use a couple of ordinary path nodes outside the entrance, if required).

Note: Your entrance must me a doorway, like that into a building, for this to work correctly. If your setup is different, you will have to add a roof/ceiling to your entrance area (I hope that makes sense, difficult to describe; think of the top of a doorframe).

Because our building is not accessible to vehicles, you may want to slap a blocking volume on the entrance, unless it is a small entrance, as this should ensure the bots don't attempt to get a vehicle in there. This should be a class blocker, set to block 'ONS-Vehicle'. You'll also want to make sure any real players, such as online, won't try to cram a manta in there sideways (This solution will work with or without a blocking volume).

You might want to make it obvious that vehicles aren't allowed inside too. Inside ONS-Surripere, I used a small flashing logo outside rather than anything solid over the entrances to clarify that fact; feel free to steal it if you have that map.

Next you'll want to configure the nodes. Set the path node just inside the entrance as Vehicle Target = True, and set the power node to that node. Note that the Vehicle Path Name node has to be just inside the entrance!

This set-up is actually pretty simple once you know how to set it up, I think you'll agree. All that is left to do now, is to rebuild and test the map!

Q&A
Here is some common mistakes/questions on why the solution has to be set up specifically as above, based on my experimentations..

What If I set the Vehicle Path Name to a node outdoors?
The bots will drunkenly hover over it in their vehicles until something distracts them. The only way they'll get to the node is on foot.

What if I set the Vehicle Path Name to a node further indoors?
The bots will assume they can't get to the target in their vehicle, and will enter/exit vehicles repeatedly, before proceeding to the node on foot. (It's a looong way!)

What if I force a path from a Vehicle Path Name node located outdoors?
The bots will still hover drunkenly over it.

Wont an AssaultPath/SpecialVehicleObjective force them onto foot?
Unfortunately, I didn't have any luck with AssaultPaths. This solution assumes that you've tried them but failed.

Doesn't the patch fix this problem?
The behavious of the white path rule may differ with later patches. However I think it is important to make a map work for unpatched versions, as many people will not upgrade their version of the game, and some may even have problems with the patches. You know that someone out there will try your map on an unpatched version!

This solution was forged by many hours of looking for a way around the problem in my own map. Feedback would be very much appreciated from those who have used this solution or those who have found alternatives, at the e-mail address at the bottom of the page.