[Bearleener]

Hi Rob, the Polo is a great ecomodding basis!
On my 1996 Golf (1.8-l, 75-hp engine) I did a total above-bumper block and no blocking below (though some would be acceptable). VW did this themselves with the mid-80's Passat (with only the holes in the VW logo above-bumper). At some point I had the impression a lot of heat was being trapped under the hood when parked with a hot engine, so I drilled a few holes in the (behind-the-grill) block.

Does your Polo have a steel spare tire well cover? My Golf wagon (estate) did, it weighed 6-7 kg so I replaced it with plywood (2 kg). Also ditched the spare tire, jack and breaker bar, using latex fix-a-flat spray instead. Total savings about 15 kg.