MPG on a TDi 300 Defender

Just having an argument with a mate. He has a very nice '95 TDi 300 Def 90 with BFG muds and a Disco transfer box and he reckons that he only gets 20mpg on average even on a run


My wife has a Disco TDi 300 and I've had several and we always get at least 30mpg - so what's going on??

Is 20 normal for a well-maintained Def 90 TDi 300?

my disco 300tdi would do a 200mile round trip with trailor and car and tools and tyres on 40 quid averaging about 28mpg and the gtw would be around 4 tonne

having driven a 300Tdi Defender for years at work i'd say that the mpg on our one was certainly far less than what i'm getting from my 300Tdi Disco, although it could have been that particular vehicle and not an average Defender mpg