Unless you're planning just short journeys, as it's a lease, the cost of maintenance of diesel, after 3 years, won't hit your wallet. If was to be a car to be kept for longer, those costs would be crucial, because even doing many miles in long trips, eventually the maintenance cost will come and it's quite high. If was the 1.8 petrol, which isn't more available (not sure, but heard that before), which would have similar suspension of the 184 diesel, then the comparison would be more about which engine you prefer. I, personally, would always go petrol (in this scenario), unless if I was doing many miles. I know about the torque of diesel, as I drive diesel vehicles also, but I prefer petrol. The 1.8 is a very refined engine. The let down is the 7 speed DSG dry. In your scenario, the 184 will be faster and more economical. Bigger brakes and independent rear suspension, that's the choice, I would say.