+ higher the front of my car with "spacers" to be equal to the back of the pickup..

thanks

+ higher the front of my car with "spacers" to be equal to the back of the pickup..

thanks

I went from 15" to 17" on my car with no effect on acceleration (actually felt it accelerated better) or fuel consumption. Just go for lightweight wheels and keep the overall diameter the same (or your speedo will over/under read). I doubt going from 15" to 16" will have much effect, unless you get very heavy wheels. Going to very large wheels (e.g. 20") may have an impact though.

if you went larger rims with a similar size tyre ( 265/70/15 to 265/70/16 for example) your final gearing ratio would actually be taller so in theory your fuel consumption should actually drop ( you will need your speedo recalibrated though)

I changed the wheels on the Vigo to some 20" and I have not noted any difference in the consumption. I do however have to say that it handles a lot better...

As V8fcorty has explained, as long as you increase the rolling diameter of the drive wheels, you ought to reduce rpm and therefore improve fuel efficiency. That might also decrease acceleration slightly, and could increase or decrease top speed, depending on the final gearing and the horsepower curve of the engine. A much higher profile might increase wind drag. As others have pointed out, there are other questions about wheel weight, unsprung weight, rim widths, etc.