Engine vs box

[kah]

Hello ecomodders.

This summer, if all works out, I'll be starting a little ecomodding project. I'm in search of a new car and have my eyes set on the upcoming Peugeot 208, but where i'm in doubt is whether to go for the smaller engine, 1.4 e-HDi with a 5 speed manual, or the slightly larger 1.6 e-HDi with a 6 speed manual. Most of our driving will be on the highway.

On paper the 1.4 offers the better FE (69.2 vs. 61.8 mpg(US)), but my experience with hypermiling (Lupo 3L and corsa 1,3 cdti 6-speed manual) leads me to think that the 6 speed manual would offer some benefits at highway speeds due to the higher gearing and better torque.

So which car hold the most potential for some ecomodding? (I would like to use this car as a showcase example for some simple ecomodding and maybe later take it a bit further.)

The first stage plans are:
lowered ride height
partial front grill block
internal antenna
ULRR tyres on lightweight alloys (possibly with some smooth wheelcovers)
Some weight reduction (removal of rear seats, lighter battery (Li-ion))
and a smooth undertray..

I have some more extreme ideas, such as integrating a 120w solarpanel into the roof and fitting a more intelligent alternator management, carbon fiber hood and magnesium wheels, but they will have to wait as they most likely ridiculously expensive.

[Ryland]

The gear ratios are going to be a bigger factor in your gas mileage then the number of speeds, do you know what the gear ratios are?