At least a few of us have. I ran one up each side. Some people recommend running them together for EMI reasons, I felt it would be safer to have them separate. It was a pain to get them to make the 90 degree turn near the door joint.

 

center/together is better to cancel EMF, and safer for emergency people on the off chance they have to saw thru your doorsill with 'jaws of life'.

I ran my cables down the center tunnel where the exhaust ran in a Suzuki Swift... in PVC conduit which was light and easy to work with as well as protecting the cables.

 

Don’t know much about Vdub’s but doesn’t the shifter rod run through the tunnel? If so make sure nothing rubs against the cables and wears away the insulation. I ran each of the cables on my Fiat through some vinyl tubing before threading them side by side through the place where the radiator pipes used to be. Been working for over a dozen years now.

 

I ran insulated conduit through the passenger compartment with the cables running through each one from front to back. Right now I only have one pack in the back seat area and just run the cables through the heating duct work from under the back seat to the motor compartment. Works great. I would consider running cable through the tunnel as long as there is NO chance of rubbing and ONLY in insulated conduit. Since the shifter rod runs through the tunnel it might be a bear at the end where the cables must exit to connect two packs together. It might just be safer to mount the insulated conduit under the belly pan and connect them there. For now, I can have one pack in the back and not have to worry about that issue. Positive cable goes through one side and the negative goes through the other side right into the motor compartment for a clean install.

 

I don't have batteries in front so I used the passenger side heater channel to run 10 ga and 16 ga for my charger and charger sense wires from the back seat area to the front where the charger is. I purchased some 1.5" diameter orange flexible plastic conduit to bring those cables up the door jamb area to a spot under the hood near the former gas tank fill tube. I couldn't fit the conduit in the floor heater channels so I used nylon wrap to protect the cables from wear. If I ever but some batteries in front there is still room for two 2/0 cables.

I used the same 1.5" conduit to run through the firewall next to the transmission (behind where the seatback would be) to the motor compartment. The conduit is strapped up high so it will clear the half shafts. I tried putting the conduit through the heater channels but there is a restriction in there and it will not fit. This way they exit at a higher location for the batteries that will go in the back seat area.

I have kept the drivers side channel clear in case I want to install a heater, but that decision will come in nine months after I experience a Southern California winter. I never considered using the center tube because as others have said, it has the shift tube in there.