On a three year lease with no intentions of buying it at the end of the lease, then any diesel problems will not be your problem. It's a very efficient engine. I averaged 60mpg over about 6000 miles in an S60 D4 184 manual, but you'll get more like 40mpg in the blunt front XC60 with autobox. Better to run it on the best fuel, which is currently Shell V-Power Nitro+. it might even pay for itself with better mpg.