Q7 vs SQ7 (2016/17 vintage)

[XM5ER]

I might be able to pick up an SQ7 at a Q7 price (from a dealer that is struggling to shift it), question is should I?

What is the difference in real world running costs and just how big could the bills get on the SQ7 if things go wrong. I hear good things about the MPG of the v8, how realistic is it? My E350 rarely goes above 34mpg, will I get similar for a motorway commute?

Any major pitfalls of either car?

Thanks in advance?

[XM5ER]

Neither of those car at this age have a hybrid. There was an etron variant around but wouldnt touch it with a barge pole.