How about your daily commute? If your office is on the other side of town, decent fuel efficiency will be a high priority. So remember, smaller petrol engines are cheaper to buy and have lower running costs in the long term than most diesel engines.
Yet diesels usually do more miles to the gallon than petrols. Take, for example, the BMW 3 Series: the official average mpg figure of the 2.0-litre petrol is 46.3, whereas the 2.0-litre diesel's average figure is 58.9. That means it's worth considering a diesel if you do more than 12,000 miles a year.
Motorway drivers will want a comfortable commute, too, so make sure you research a car's refinement and ride quality our group tests and car reviews on Whatcar.com will help you out. Try to book a test drive with at least a few of the cars you're looking at, too, and take them on part of your daily route if you can.
Finally, and crucially, think about cost not just the list price, but how much you'll be paying to fill-up, insure and maintain the car. Think about how long you'll keep it, because you also have to consider resale value. Our Real Cost figures, listed on our website, take all these outgoings into account, and they'll also help you to narrow down your choice.