Which engine will consume more gasoline @ 100mph?

Question

Suppose you have 2 engines, both 4 cilinders. One has a capacity of 2000cc, the other 1600cc.
I am wondering which engine would consume more gasoline if you would drive (with the same car and in the same wheather conditions ofcourse) at 100mph (= about 160 km/h).
Can a 2.0L engine burn the gasoline more efficiently at such a high speed?

I'm curious about the outcome :)

Answer 1

All other things being equal, assuming that both engines are just as well designed, and capable of running the car at that speed without going into a out-of-condition mode, and use the same fuel, have the same compression and torque curve, etc; then the 1.6 l will be more efficient because it will be lighter, will have less internal friction (smaller components), and less thermal losses.
If the smaller engine is out of breath, then of course, it will start becoming inefficient.
There are just too many variables to consider to decide which conditions make one engine better than the other, like the weight of the car, its aerodynamic efficiency, the transmission gear ratio, etc.

Answer 2

The engine with more CC will always spend more gasoline. Compare MPG for a fast BMW versus your midsize sedan. Or better yet, let's reduce the number of variables with a real world example. 2006 Ford Mustang, which is made in 4.0L engine (1 L = 1000 CC) and 4.6 L engine; the 4.0L has 19/28 MPG, while the 4.6 L gets 17/25 MPG - clearly, the one with the bigger engine spends more fuel, both at city speeds, and highway speeds.


http://autos.yahoo.com/2006_ford_mustang/

You will see the same thing if you look at any other car, say a 2006 Nissan Altima.

http://autos.yahoo.com/newcars/model/overview.html;_ylt=AiM7a366K888MUo8LX7dg3cEc78F?modelId=4618