Yeah the 4BT was considered since I have a couple ve-pumped motors sitting at work (my paycheck has a big C on it
) but decided to go with the TDI for a few reasons:
1) half the weight
2) MUCH better NVH
3) electronic control of injection quantity and advance
4) better mileage
5) better hp/torque ratio out of the box
6) smaller package size
Of course there are drawbacks
1) more complicated swap if electronic pump control is maintained (you can retrofit an older mechanical pump from a 1.6TD)
2) more expensive
3) less robust block...lower power capability. Period.
Please don't take this as a VW tdi is better than 4BT post. I honestly don't think that. They are two very different motors and are both perfect for use in a Ranger.