Fuel Consumption RPM MPH

the closest you'll probably come to is fueleconomy.gov

and the only rule is there are no rules, because my 5.7L Firebird gets better real world fuel economy than my co-worker's 2.5L Cougar.

Not necessarily.

Depends on what manufacturer you are talking about. The factory engineers have such specs, but it might be hard to find it on the net. One thing is for sure. If all else is equal , then the faster you go the more fuel you will consume.

There again, you can't compare apples to oranges. You need to have all other variables the same to come up with the sort of figure you are talking about. Different cars have different gear ratios in the transmission and differential as well as different size tires based on which size engine they have in them. All that has to be taken into consideration.

The engine displacement is one of the things least affecting the total fuel efficiency of a vehicle. Many other factors must be taken into consideration. The aerodynamics of the vehicle, gear ratios, type of emmission controls, weather or not it is naturally asperated, etc., all affect fuel economy. Basic engine design plays a lot into how efficient the engine will consume fuel as well. It is just not as simple as saying a larger engine burns more fuel, because you have to factor in the weight of the car wind resistance and all that other stuff to get an idea of how efficient the vehicle as a whole will be.

Kevin

To be more specific - Toyota Camry V6 or Nissan Altima 3.5.compares to Camry 2.4, or compares to Nissan Altima 2.5 - all driving same road (same tires, etc.)

Kev> > I think rating fuel consumtion for comperasion purposes can be > > misleading.

It depends. Here are some of Consumer Reports' results:

Toyota Camry 3.5L: 32 MPG highway, 16 MPG city Toyota Camry 2.4L: 36 MPG highway, 16 MPG city

Chevy Malibu 3.5L: 38 MPG highway, 18 MPG city Chevy Malibu 2.2L: 38 MPG highway, 16 MPG city

Are you trying to justify to your spouse the extra cost of a V-6? :)

For what it's worth I drove both the 4 and 6 cylinder version of the Camry. In my opinion they both were very powerful engines that are appropriate for that car. If there was a difference in acceleration it was so small that I could not notice it. If you really concentrate when the engines are at an idle, it is possible to notice a slight more vibration from the 4 cylinder than the 6. Otherwise it is a push. I read somewhere that Toyota developed the V6 for the USA market because people there like engines with more cylinders. It helps sell cars.

The V6 because it is a bigger engine will probably use a little more gas at highway speed.

I d> To be more specific -