Nissan almera s1500cc 2003?

Recently purchased almera, smooth walking but orange malfunction indicator light comes on for short periods and its drinking petrol, only getting 28 mpg. rarely take the engine over 3000 revs. all reviews for car and year suggest better mpg. any suggestions other than take a taxi because it would be cheaper?
Answer
Could be lots of different things causing this problem. get it around to a nice garage. you say recently purchased, if bought from a garage, take it back.