TH Exec 3L how often does it update? 5mins? 10?

it really depends what your instant fuel reading is, if you sit on 12L/100km and you instant is 6.x/100km it will drop down from 12L/100km reasonable quick if you hold it around 6L/100km

if your average is 12L/100km and your instant is 11L/100km. dont expect it to move very far

it took me 4 hours driving at 107Km/h to go from 11.9 to 8.2 in a 3.5L with an instant around 6.7L - 8L

Instant fuel reading "appears" to update every three to five seconds. Average fuel must update after X amount of instant fuel updates. You'll notice your average fuel reading fluctuating a fair bit for the first ten kilometers roughly.

Wonder if there's anything about this in the manual?

it really depends what your instant fuel reading is, if you sit on 12L/100km and you instant is 6.x/100km it will drop down from 12L/100km reasonable quick if you hold it around 6L/100km

if your average is 12L/100km and your instant is 11L/100km. dont expect it to move very far

it took me 4 hours driving at 107Km/h to go from 11.9 to 8.2 in a 3.5L with an instant around 6.7L - 8L

Depends on how many km the 11.9 represented - if it was over the previous 10 000 k it will take ages to change, if you reset it at fillup, did 10 k at 11.9 to get to the freeway and then an instant of 6.7 it will change quite quickly

Average is total fuel used (since last reset) / toatal KM (since last reset)

Instant is (I guess) fuel used in last "x" seconds / distance trravelled in same time

thanks guys , much clearer now. no handbook can be a pain at times with a new car.