Every week a Guardian Money reader submits a question, and it’s up to you to help him or her out – a selection of the best answers will appear in next Saturday’s paper.

Our elderly estate car doesn’t have air conditioning and we’ve been suffering this week. We already have an in-car garden sprayer to mist water over each other but I need more proven tips to keep cool on the move. Do those window shades work? I really don’t want to have to trade the car in.

Do you have a problem readers could solve? Email your suggestions to money@theguardian.com or write to us at Money, the Guardian, Kings Place, 90 York Way, London N1 9GU.