The size of vehicle you choose will have quite a significant impact on your fuel economy, so you want to choose the smallest vehicle you can that is still big enough for your needs. Unless you need the height of an SUV or the load space of a van, an estate of the right size would give you the boot space you need but with the comfort and economy of a car. Another Octavia Estate or a Toyota Avensis Tourer would be a good choice as there are a good number on the market to choose from, they both have strong reliability records and a choice of efficient engine options whether you go for petrol or diesel. The average annual mileage in the UK is 7400 miles, so if you need to travel further than this there isn't a great deal you can do to mitigate it, but staying on top of maintenance will help to maintain its value even if the mileage is higher than average.