Hi Nicol! Your observation shows that you are doing good with learning the language. Good job!! However, λίγο can be used as an adverb, but not in this sentence. Examples: Κάνε ºλίγοº στην άκρη. Step aside ºfor a bitº. Πες μου ºλίγοº τη γνώμη σου. Share with me your opinion [briefly] (λίγο as briefly). You can't buy things briefly or for a bit (reference to time).
We have been asked if "petrol" can be used in this sentence and of course it can...as well as "gasoline" and "fuel".
We should point out that "gas" is used because Duolingo teaches American English, but of course we accept all other correct versions. As shown above, as well as "biscuits" for "cookies" and "colour" and "shall" for the first person, also "have got" and as many more are needed.
Yes, I feared something like that. Everything except the straightforward translation sentences are chosen by the Duobot. For some reason, it all too often chooses some obscure or even deleted options. But mainly it only accepts the first option given although there are other correct options as in this case. We have reported it regularly and will continue to do so. I am sorry and thank you for the input.