Why has my Nissan Qashqai had worse mpg since the engine computer system update?

I got a Nissan Qashqai 1.2 petrol from a main dealer at 9 months and 6000 miles and have run 3000 since then. Do you know anything about the recalled engine computer system update? On the first service the dealer said two recalls were to be added to work. One for wheel arch plastic fitment and one for engine computer management system. When I asked for details they said "don't know". In the few journeys since then I got impression that the mpg was a little down. I get 38mpg on run of 30 - 50 miles on A and B roads driven gently. The recent run was nearer 33mpg.
Thank you. That's interesting. There have been some reports of high oil and fuel consumption from this engine in Nissan and Renault, so I wonder if the software update was to adjust the fuelling. I'm speculating here that the engines might have been overfuelling slightly, washing out the engine bores and this led to the oil consumprion issue, but it's just a guess.
Answered by Honest John on

Ask Honest John