Currently getting through about 1.5 litres of coolant every 500 miles (I do a high mileage so this is actually only over a few days!). Been losing a little recently but now getting pretty bad. Going to have a look over the weekend and see if I can trace the problem but could use some ideas where to start.... car is '98 1.9TDi, no puddles or drips appear under the car, no obvious steam or dried coolant around hoses when looking under the bonnet. Car starts and runs the same as ever, no loss of power. Temperatures the same as usual. no wet carpets either! any suggestions?