For example 8L/100km @ 80km/h
First thing I did was get the time I would take to complete 100km with my current speed
$$ \frac {100 \text{ km}}{80\text{ km}/\text{h}} = 1.25\text{ h}$$
then $$=\frac{8\text{ L}}{1.25 \text{ h}}$$
$$=\frac{800\text{ ml}}{75 \text{ m}} $$
$$= 106.6 \text{ ml}/\text{m}$$
Is this correct? Thank you