my yaris, courier driving

[jdleafs]

I've been reading through posts, and i'm really impressed by the fuel economy some you guys are getting....some people are getting around 700 km's a tank, that is crazy good....for me i see 400 kms when the last bar is blinking. That is peanuts compared to some of you but i have a lot of factors working against me- #1 and most obvious is how i run my car-from 830am right until 5pm, i'm on the road delivering packages-all city driving very short trips usually. There are other facors like climate and road conditions, but the nature in which i drive my car compared to every one else is why i yield such poor results- i was hoping to get better mileage out of this baby for the work i do, i'm kinda disapointed, the gas mileage is similar to what i was gettting with a 2000 corolla/ with that being said i absolutely love this car, tough as nails. Anybody have any insight, should i be concerned. Also is it better to put around 35psi instead of low 30's for tire pressure?