When I start up my 2003 petrol car, as soon as it fires I often give it a dab of the throttle, so the battery recovers. It's fuel injected, no carburetor or anything.
I've been told this is pointless.
Does giving a dab of the throttle when I start my car have any benefits?
I have no starting problems or anything, it's just something I've always done in winter.
No, there are no benefits to giving your car throttle immediately after startup. This extra throttle will not recover the battery from the amount of power you just used to start the car any better than it will by just driving immediately after you start up. Also, given that you have a fuel-injected vehicle, there's no need to warm up the engine for more than a few seconds in the winter before driving. That some people feel the need to do this is either for their own comfort (you get hot air faster) or it's a remnant of the mindset from the days of carburetors.
Please see my response here for a similar question.
The best thing you can do for your car in the winter is start it up, scrape the ice of the car if there is any, and drive. In this short amount of time, it'll be warm enough to start driving it.
Unless you are holding the throttle down to let the car idle at a higher RPM than normal (which can help the car warm up faster), what you are doing shouldn't have any side effects at all.
It's generally seen as okay to give it a little gas and have it idle at around 2k RPM to help it warm up. As long as you keep the revs down until your car is warmed up, you should be fine. I have an 03 Subaru Forester, and I just take it for a light drive around the neighborhood before going anywhere, all while keeping it under 3k (I never really go over 2.2k during this time either).
