Peugeot 407 for good economy and reliability on Diesel variant, Citroen C5 too as long as you part ex before they reach 200,000 miles. This is when they start to become expensive.

For British cars, I would choose Vauxhall Vectra or Insignia, follwed by late model Mondeo, all Diesel powered.

One tip when doing Cabbing with high mileage on short journeys, do Oil changes twice as frequently as recommended. I used good quality semi-synthetic engine oils with a decent replacement filter, cost about £45 inclusive of labour and parts and engine will cover high mileage no problems.

When buying a car for this trade, do internet searches through some of the main dealer websites and be prepared to travel a bit. I found a good Citroen C5 Tourer Diesel (top of range) with 27,000 miles and 4 years old for a third of the cost of a new one.

Good luck with the cabbing