Last reply was an attempt to point to the supposition thing and its NOT being any kind of statement about Pumas being better than any other defender. Last response hopefully made it clear that I supposed its those people (with defenders scary at speed) who perhaps don't know how good TDCIs are at speed.
Now to specifically respond to your statements and questions:
The Defender that inspired the exact terms I used (struggled to reach 100 and was a white knuckles scary ride) belongs to a fellow who is barely an acquaintance and we happened to both be on a trip organised by mutual friends.
On the highway transit home (7hr drive) we stopped for a meal. Convoy lead raised the travel speed topic, "Is everyone happy to continue on at 100kmh?" (The highway speed limits 110kmh). I ventured to suggest its ok to up to 110 if thats ok with others. The acquaintance asked to keep it at 100. So it was agreed to convoy at 100.
Chit-chat then touched on speed. I said that when not in convoy and far from traffic and speed police I don't hesitate to sit on 140 for long periods. Acquaintance then regaled how much hard work it is to keep his defender inside the lines at speeds over 100.
In the nature of good hearted banter we ended up trading keys. He drove mine. I drove his. It was a scary white knuckle experience for me, and a struggle to maintain 100kmh on anything but dead flat, or downhill sections. The experiment terminated in less than an hour. I wanted my TDCi back!
This led to my "uncertain belief" that it is perhaps people who have experienced defenders that struggle to reach 100kmh and are scary at speed - who don't yet understand how good the TDCi is at speed.
Answering your question, directly, in two parts:
What Defender struggles to do 100?:
THAT Defender in the story above struggled to make 100 and is definitely scary at that speed (no specific grouping like "all TDi's" was implied in my writing)
What makes a Puma so much better at that speed?:
TDCi's generally, as a vehicle grouping, and the 2.2s specifically are
- newer
- quieter
- have a lot more get up and go still in reserve (safer overtaking etc)
(Probably more but I am getting tired of my own writing - the rest of you must be positively sick of it.)

