Thanks for the heads up, buddy!
Certainly agreed, night life is nothing that one would really need, in the end, we all are social beings and there is other ways of fulfilling this need, like weddings (as mentioned :) ) or direct personal contacts. So in that way it's not really preference, it's just truly culture and how you grow up. As a Westerner, it might be a bit of an issue. I lived with an expat and he said one of the major reasons he does Couchsurfing is to socialise.
The thing with the cheap petrol is that it is only for Bruneian number plates since it's subsidised by the state. As a foreigner, I had to pay BND 1.10/litre (versus 50 Brunei-Cents for locals). On the Malay side, it's cheap anyway, around 50 US-Cents per litre. So I wasn't bothered too much by this policy. :)