1ECU 2 Maps - possible?

How exactly is this possible? Is this a cheat which only activates the power remap once the switch is on, or is it really 2 maps on 1 ecu?

I can see an ecu for sale on ebay for 645, which says it has 2 maps, one with full power and one for fuel economy.

I've been having a dilemma bout whether a remap will increase fuel consumption and reduce mpg...this seems like a nice solutions its true. Though for that price...

Would a power remap increase or decrease ful economy, i've heard so many different versions that i wonder who is correct and who isnt...

You can not get something for nothing so a remap aimed at producing more power (bhp) will reduce fuel economy. However a remap aimed at increasing usable torque often leads to better fuel economy because you do not need to change gear so often and can run in a higher gear. Horses for courses.

There are firms offering switchable maps but i have no idea how they do it.

the ones I have seen have 2 ECUs in the box, either piggy backed to the original, or a bespoke box with 2 ECUs in it, so it just switches between the two ECUs.

Not sure about Land Rover but my last car (Mitsubishi Evo) had the ECU flashed to enable dual maps. Still 1 ECU but some clever guys managed to unlock the code.

Well I already drive pretty sensibly, and do mostly urban driving so i don't think higher gears for longer will do much for me...

Anyone who did remaps, can you give opinions on how thirsty its become? I'd like to give my TD5 more ooomph, but seeing that its my everyday car, i dont think i can afford a higher fuel bill than i'm paying right now €40 every 6 days or roughly every 180 miles...