Diesel engines have very high compression ratios, not combustion. They do not have much horsepower ... but a lot of torque. A Lottttttttttttt of torque
If you aer going at 60 in 4th gear .. and you have a a petrol and diesel car, and you push the gas in the same gear ... the diesel will leave the petrol in dust until the petrol car revvs up.
Diesels have LOW end torque, excellent for city driving. But in Pakistan, the only diesel u get is the patehtic 2C Corolla, a 70s engine. So here, unless your looking for an econo sub 2 lakh car (sprinter diesel converted or a fiat uno or charade/starlet diesel)... dont get a diesel.
The Corolla DIESEL is teh most pathetic car that you can buy today. A 1970s diesel piece of crap sold at a price of 20 lakh! Common rail diesel engines are epic ... perform pretty good, good economy too. But those cant work on our diesel which has a high sulphur content.
Fun fact, the 24hrs Lemans was won last time by the Audi DIESELs. Their economy made them pit a lot later than other cars.
CNG Diesel kits are available. But they still use a bit of diesel for combustion. Unlike petorl engine, diesels dont have spark plugs. The combustion occurs due to diesel being compressed to a ratio of 22:1 (usually) ... so when using CNG, you need a lil diesel for a spark!
I personally would say a good tuned petrol car can be economical. Ive gotten close to 16km/l out of a manual vitz and honda city i-dsi. Properly tuned and driven with a lgiht foot. 15 from 2001 city.
DIesel is a lot better than CNG. And if you need a choti car (mehran khyber) ... keeping a diesel one is a lot better than CNG. You wont have any problems driving in teh city with a/c on 5 people in car climbing bridge etc!
