I have the 5AT in SS mode, but this would apply to 6MT as well. If I'm cruising at 50 mph and want to accelerate to 70 mph, which method is best for fuel economy?

1. Leave the car in top gear, increase throttle and slowly accelerate.

2. Maintain current throttle setting, downshift one or two gears to put the engine in a better powerband and accelerate.

3. Downshift and increase throttle to acheive fastest possible acceleration and reach 70 mph sooner.

 

Put me down for #1. followed by 2, then 3.

 

I second fdl. The whole "get to a faster speed sooner" thing doesn't help mileage. If it did, I'd peel off the line everywhere, and so would everyone else.

 

#1 for sure if you want better gas mileage

 

4. Leave the car in top gear, and quickly accelerate (wide throttle opening). Low revs wide throttle opening = efficiency.

 

Research has shown that applying 2/3 throttle in most gears and getting to desired speed quickly is the most efficient.
I vote for 1 with 2/3 throttle applied.

 

 

Not exactly. Low revs + WOT = volumetric efficiency (more air in the cylinder per intake stroke). But A/F ratios being equal, more volumetric efficiency means less fuel economy (more air = more fuel).