Gas mileage: one long trip vs repeated trips

[hungt1999]

I have an 98 altima 5-speed, all stock. I do mostly highway driving. I noticed that on a single long distance driving of several hundred miles on the highway, I can get about 35 mpg.

However I only get only about 25 mpg if I do highway trip over several days. I is like every time you run the car and shut the engine down, some fuel in the system is lost, maybe something to do with our infamous charcoal canister, I dont know how to test that.

Anybody have experienced this?

[anthony.bib]

eh...its kinda normal, i mean if you have the engine set at one certain speed for a long period of time it dosent have to warm up/do any tranny loss of power/produce power more efficently because ECU adjusts to the RPM... Theres a number of causes.