I use Jizer (degreaser) and a bog brush to clean the engine bay. But usually I go for the 'keep the bonnet closed and it'll go away' method!!!
To work out MPGs I usually brim the tank, reset the trip miles, then next time I fill up I brim it again and look at how many miles are on the trip counter.
So you know how far you've gone and (if you remembered to keep the receipt from the garage!) you'll know how many litres that used. Then (because I'm a maths tard) I search for 'MPG calculator' on Google UK (I believe US gallons are different to UK ones? Anyone confirm this??) and that'll work it all out for you!
