Gas mileage problems?

[Paakkjuh]

Hello. 
I bought used toyota iq 2010, 150k. Had troubles with poor performance, did the usual stuff, changed the plugs and had the egr valve cleaned. Then the shop found that the oxygen sensors dont work. Funnny thing, didnt trigger the check engine light. Anyways, they changed the sensors, but said maybe the kat is gone, too, they dont know(Im not sure any more they are such great mechanics...)

Anyways, the car goes better but the fuel consumption is still quite high. Average 6.9-7 l/100km or 33mpg small city driving. On a highway 4.5-5l/100km. That seems a bit high for this car?

what fuel consumption rates do you get? I still have warranty if there are hidden faults..

[FROSTYBALLS]

Presumably you're in the US as you're using US gallons in the conversion. Highway figures are 47-52mpg (US).