Guys,

We know the Lotus Elise S is pretty close to what a good 818 will be in terms of power to weight ratio. So the performances of the small Lotus is a good indication.

However that wasn't enough for me to picture the whole thing. lolll
I have found another car (there certainly are plenty, but just came across one without looking for it and the results are very interesting) which is also pretty close to I think what can be a slightly supped up 818.

http://www.topgear.com/uk/photos/a-c...-05-2013-07-03

This car has 400bhp per tonne (285bhp engine, so it weighs around 712.5kg).
If we estimate the 818 to be 850kg (I am a little conservative here), it would require the car to have 340bhp in order to reach 400bhp per tonne. 340bhp is 289whp from the engine on the dyno at 15% loss.
Now for the torque comparison, that weird car on the link has 310ft-pds or 435 per tonne.
The 818 would have to have 370ft-pds to be equivalent (435tq per tonne), or 314.5wtq at 15% loss on dyno. Which is VERY easy to reach!

Recap:
818 with 340bhp/370tq (289whp/315wtq) = that above car with 285bhp/310tq.

Now the figures on that weirdo:

0-62 in 3.7 (0-60 probably in 3.5 or 3.6) and top speed of 152mph, but that's gearing anyway so let's not look at that.

That being said, EVERYTHING else being equal an 818 with 289whp/315wtq may well crack 60mph in about 3.5sec.
But the next 80mph must also come up quick!!!!

Oh, that weird car above costs GBP70k. And I don't like it.
The 818, USD$15-20k for many people. And I love it.

So for some people (like me!!) who wanted some comparison and numbers, I am served well.
Of course, that is with the assumption that EVERYTHING else being equal, the famous ceteris paribus in latin.