You need to be careful about buying an older diesel. They can suffer from a wide range of issues and can be expensive to repair. This is especially true if you don't cover many miles, or use the car for a lot of short journeys. In this case, the diesel particulate filter (DPF) can get blocked. Even if you do cover high miles, you might find that a low-mileage example already has issues when you buy it. For that reason, you might be better looking for a higher mileage car - a used Astra diesel that's done 120k miles on the motorway will be a much better option than one that's done 60k of short journeys.

If you're not covering lots of miles (more than 12k a year), you'd be better looking for a petrol or hybrid alternative. How about a Toyota Prius? They're popular with taxi drivers for good reason - they're extremely reliable and cheap to run. Alternatively, consider a more conventional petrol choice like a Honda Civic.