tell me about fuel economy in car,petrol or diesel?

Answer 1

Hello,

petrol engines generally have a higher consumption because of the lower thermal efficiency of the Otto-cycle. Diesels are more economic and diesel fuel is usually cheaper (at least in Europe :D). the bottom-end torque of the Diesel is better, but at higher rpm's the power quickly disappears, forcing you to shift frequently. In contradiction, petrol engines have their peak torques in the mid-range rpm or even higher. Thus, with Diesels you get a better fuel economy but a very narrow power band at low engine speeds (e.g. 2500 rpm), while with petrol engines you get a wider power range going up from around 2000 rpm all the way to the redline. For petrol engines, the emission reqiurements are easier to conform to. Diesels have expensive components, a failure in the injection system can cost a lot. There are no naturally aspirated Diesels novadays, so extra care should be taken that you are driving a turbo-engined car (e.g. you must not floor it when the engine is cold, and you must not stop it after a hard run).

Your choice :D

Answer 2

I posted this on somebody else's question but it also applies here: If you're doing highway driving, then drive at a lower speed and use cruise control. The power required to drive at a given speed increases exponentially. A difference of 10mph will significantly improve your mileage. Pick a moderate speed you're comfortable with. You won't get run over, just settle into the right line and turn on the cruise. Before long you'll find yourself in line with other like minded people. Whether city or highway, don't leave at the last minute, leave enough time so you can drive calmly. Gentle driving saves fuel. Avoid heavy throttle - this puts the car's computer into "enrichment" mode, where it deliberately runs extra rich to protect the engine. It does not run a well calibrated fuel mixture in this mode. Don't use AC if you don't need it. Some people run it constantly. Windows down is more efficient than AC. Maintenance - if you have a check engine light on, try to find out what it's complaining about and fix it. Some issues affect mileage. Pay attention to all the typical tune up stuff, especially ignition. Fuel injectors are another biggie but that's normally not an easy part to service. If you do your own car work, consider replacing the upstream O2 sensor(s). The upstream is before the catalyst - the ECM uses it to keep it's fuel mixture in calibration. They lose accuracy as they age and cause the engine to run slightly rich. The ECM can't notice this unless it completely fails. On some cars these sensors are cheap, but on newer cars they get expensive. Mine was cheap and I tracked a mileage improvement of 10%, so it paid me back fast. They should probably be replaced every 50-100k or so, but yours might be expensive on a 98 model so it's not always an easy decision. No guarantee this would help, but often it does. Make sure tire pressure isn't low. Make sure your coolant temperature is getting up to a normal level. If you notice it's running colder than it should, find out why. Running cold hurts the mileage. Of course running too hot is a more common problem and you *really* don't want that either as it can easily cause serious engine damage, especially with aluminum heads. Basic engine health is a big factor as well. Don't let it run low on oil or fall behind on oil changes. An engine that runs but is unhealthy will get worse mileage.

Answer 3

Diesel is best for economy they pull low down enabling you grab higher gears sooner which increases the mpg and there much easier to drive and faster than small engine petrol powered cars.

Answer 4

If you have the exact same car one being diesel and the other petrol the diesel should get better mpg. The petrol vehicle should have better acceleration, but you didn't ask that.

Answer 5

Diesel gets the best gas mileage and is the same price as a regular gallon of gas..but diesel motors are more expensive to maintain