Correction...
Likely that a diesel engine will have a similar or higher power output to a petrol engine of the same capacity, yet will have substantially more torque and will produce both power and torque at much lower engine revolutions and have >25% better economy... if the petrol engine is turbocharged, then it's likely that both power and torque will be much closer, but then the fuel consumption gap will widen.
Reliability of diesel vs petrol is unproven IMO... both have the capability to be both reliable or unreliable, depending on the manufacturer, not on the fuel type.
Overall, diesel is a better fuel for non-sports cars than petrol.