older versions were 3 speed forward and need high rpm to achieve high speed, consequently poor fuel consumption by default. Then people converted to cng that messed up these hi tech machines.
I think models after 2000 have good average just because these are 4 speed forward. Twice I have tested my 2011 model and it touched 132km+ speed and it does not mean that I will push it again and again. I keep the speed upto 100 on highways and it is doing the job. But one should really take care of these small engines. I used liquimoly gear oil, high tech LM engine oil, regularly change filters etc.