Dropping an AS level?

Hiya, I've just started my AS levels (last September) and for the most part they are going very well. I've taken maths, physics, chemistry and economics. The first three I am really enjoying but I find it very difficult to enjoy or get excited for economics.

Maths and physics are going especially well but chemistry is a grade behind them (I'm predicted a low B). I am considering simply dropping economics to do three AS levels and carrying on to do all three at A2. This is how future AS students are doing things anyway, isn't it?

My reasoning is that the four hours a week I spend in economics lessons and the further three hours I spend completing economics assignments will be put to better use bumping my chemistry grade up and hopefully securing my maths and physics grades. Furthermore, I see no point in continuing a subject for which I have no real interest in.

Do universities really care for applicants having four AS levels and is the possible improvement in my other subjects worth the lack of an AS qualification (though most probably a fairly low one) in economics?

I hope to study mechanical engineering at university.

I'd appreciate any advise or feedback I can get, thanks!

Some universities do require you to have a 4th AS level, so just check with their website just in case