The Volkswagen Up is a really good car but not without its faults, unfortunately: www.honestjohn.co.uk/carbycar/volkswagen/up-2012/g.../. If this doesn't concern you, also consider the SEAT Mii and Skoda Citigo - they're essentially the same car but a little cheaper. The Aygo isn't without its issues, either, and feels flimsier than the Up. I'd look for a Kia Picanto - it has fewer problems and is a great little car. I'd prioritise condition and service history over mileage or age, but there's no reason why you can't tick all the boxes with a £4500 budget.