Toyota Passo 2016 model average issue

[pwuser167354798477]

Hi,
I have recently bought toyota passo 2016 model. I have been facing patrol averages issue, that I cannot understand. When i bought the car, it was giving 15+ average to previous owner. when it was handed iver to me and i drove it for 2 days the average got low around 14-14.5, but i thought its fine according to my driving pattern. Then i refuled it and went to mechanic for normal tunning etc he did ( oil change toyota 10w30, clean plugs, change air filter, clean throttle etc ). Then the car started going down on average and eventually it came to 12km/L.
then i had to travel on motorway and refueled it again, then meter was showing continuous 13km on motorway. i travelled around 370km and meter was showing half tank still left but it was showing it can only be driven 200km on the remaining fuel. but again in city the average got even lower.
sorry for all the write up, but i am really worried. can you guys help me to understand what is happening??

[hash4u]

spark plug changed?
market is full of fake spark plugs
also who told u to use 10w 30?
if engine is not burning oil stick to 5w 30 oil

try disconnecting and reconnecting battery after few mins
try cleanng o2 sensor

[msabbasi]

To @hash4u valuable comments I will add why did you "service/clean" the throttle body? No need to fiddle with the throttle body. Just make sure the air cleaner/filter is well looked after.

If you are in the twin city area, visit Toyota GT Motors. They have knowledgeable techs who are very good with scanners and live data interpretation etc. My son's both Passos were looked after by them and I found them to be very good at tracking down problems.

[pwuser167354798477]

They didn't change the plugs, just cleaned them. mechanic asked me about previous oil, it was zic 10w40, then he changed it to toyota 10w30. disconnecting wires I'll try and mechanic also cleaned the o2 sensor

[pwuser167354798477]

i recently took over the car and asked the mechanic to check everything, engine oil, spark plug, brakes etc

[the_mira_guy_08]

Switch to 5w30. If no reduction in oil or blowby, 0w20 is best. Throttle body is only cleaned if it's actually dirty not frequently.