[echo-francis]

430km seems low for a toyota echo. maybe your car is not in good shape. do the regular maintenance and mabe you will have better results. if thats not the problem maybe its you or your commute: a short commute will kill the fuel economy (look at my fuel log).if i would want to make 430km on a tank i would have to drive really fast(minimun 20 over de limit) accelerate and brake really hard in town. but i dont think you do that but if its the case, the problem is there.

i was able to do more than 1000km because i was ready to make a normaly 10hour trip in 14hour .all the mods i have are there because i am crazy and i allways want more and more... i think my mods count for about 25-30% of my amelioration thats means that the other 75-70% is from my driving style

i recomend you to read this
65+ Vehicle modifications for better fuel economy - EcoModder.com

and this
100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com

and explore the forum because there is so many helpfull information