2,500km oil change interval recommended by Toyota Pakistan is really an overkill and has been designed keeping dealerships profit margins in focus. Back in late 90's I kept a 2.0D bought brand new for almost 150,000 kms with oil changes at intervals of 5,000kms using Caltex Delo. Even after clocking 150k kms engine was as sweet as brand new.
2.8D definitely makes sense for people with higher mileages and also for people who use their vehicles for trips to interior and up north. btw if somebody is not planning these trips, he should purchase a good sedan like honda civic or audi etc. instead.
2.7 Petrol average is over stated. This engine never gives more than 6~7 kmpl. Whereas 2.5 D4-D or 3.0 D4-D never come below 9 whatever the road condition or driving style.