I see you are on a roll - so let me give you some feedback now. Our main concern with many of the designs coming in at this point, is that they are feeling a little flat/serious, and we are loosing a lighter happier feel. This may mean looking at a different, less obvious colour palette to bring it to life as a start. So we like the less serious feel of your design - my specific issue with #35 is that it looks like the front of a car badge, and we don't want to get into the car/sparkplugs territory. We see that when we stach Spark on Plugs, what pops out is 'Park Plugs'...which also is not working.
We are also finding many of the entries very business-to-business feeling, and also edging too much on the side of overly masculine colours - and many are also rather tech/cellular networky (I know that is not a word :). This takes away the human element and also makes them look very cold, serious, and techie. Which is not what we are aiming for. Please can we also watch that the emblem does not end up looking like a Superman logo.
I think it is worth just running your eye once more over the target market overview in the brief, as well as the brand personality.
We need a young adult, almost sporty feel - Brands like Converse, Nike, Red Bull, Puma, MTV, Levi's, HMV and so on are very much in our target market repertoire of top brands and appeal to both the guys and the gals.
If you have any specific questions for me, feel free to ask.
I've come up with an alternative idea, however the company name sparkplug screams the obvious
a spark, star, flash etc and of course a sparkplug the dilemma reminds me of RIM (Research in Motion) back in the day. Long story short the marketing team and RIM (now Blackberry) told me flat out that the fruit blackberry would never be associated with the company, Funny how that changed a few years later with the icon that represents blackberry the fruit.
So how do we over come the immediate association of a sparkplug witht he company name, easy. The concept I've come up with is based on the Mythical character Mercury.. and I have associated 2 new taglines for consideration.