The Puma's seals are very good on mine.  We completed 25,000km around the country including sections of bulldust and the Bullman track twice without cleaning the inside of the Defender.  It never got that bad.  When we got home it was noticeably dusty on the black dash but no worse than my D1 or D2 and nothing anywhere close to what my Defender Tdi gets like.
I haven't read all the preceding posts but I'll assume its already been stated.  Keep the A/C (or when down in the cold, the heater) on when needed, keep the system on fresh and NOT on recirc.  The only times we put it on recirc was when we were driving through smoke blowing across the road from fires and then only for the short period needed.
Also check your door alignments, mine were really poor and periodically check your back door windows as, like every other model Defender, they will vibrate open up to about 1".
				
			 
			
		 
			
				
			
			
				MY15 Discovery 4 SE SDV6
Past: 97 D1 Tdi, 03 D2a Td5, 08 Kimberley Kamper, 08 Defender 110 TDCi, 99 Defender 110 300Tdi[/SIZE]
			
			
		 
	
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