I found some cheap plastic in the basement today so i thought I would make a prototype grille block until I get some polycarbonate/perpex and do it properly.
I was going to attach it the front, but the grille mounting bolts behind made it very easy to attach and it makes it more stealthy.
I had a quick run out to the shops in it, temperature didn't go any higher than usual, but to be fair I only done 30MPH. I think (& hope!) the engine temp will rise a bit once in 5th gear and doing 50-60mph, because now I am at 88°C and the fan doesn't come on until 102°C, so I have a lot of room to manouvre.
I haven't had chance to check if it affects FE. But this and my lower grille block installed the other day should hopefully yield some results.