Maybe exhaust gasses. But from thing's I know that can cause bad egg smells
leaky exhaust, catalytic converters can give off an eggy scent. Could be your washer bottle, infected with smelly bacteria (or any other pool of standing water. Check your door drains, windscreen run-off drain, etc, are clear from obstruction) Could be a faulty alternator, putting too much power into your battery, cooking it (releases a distinctive sulphur smell). Pretty sure it shouldn't be anything I have mentioned being so new but worth checking I guess.