where do I get proof of manufacturer data (sprite consumption)?

Hello, Where can I find actual manufacturer information about fuel consumption via my Daewoo Evanda 2.0 CDX ? My lawyer, who has been representing us for more than a year, tries everything so that we can withdraw from the purchase contract. However, he says, “Internet information does not help us to prove fuel consumption. We need proof from the manufacturer” First reason: Dealer stated that the gas consumption is 7-8 l; we have found a much higher consumption (15-17 l). FZ did not come due to many defects by the TÜV (which is why a judge of the court could not determine the gas consumption). However, he had the vehicle picked up anyway, in order to find out afterwards that it has enormous damage due to 1-years of service life, so that he could not determine the gas consumption…… – think he will be able to calculate his catalog-like report expensively… – only, everything is fixed on “VERSCHLEEß”…) second reason: today have e doubtless found that a reimport was subjugated to us. Please crawl into your documents, you can find something about the actual manufacturer data of Daewoo.