When starting my new 2010 GS auto this morning, outside temperature was 7centigrade, a few seconds delay frm pressing start button till starter engaged, turned over slower than usual making unusual noises then started as if not firing on all cylinders, lots of black smoke. Have covered 1400 miles.

Did 50+ miles and all seemed OK, drove well, no power problems or smoke and for rest of day started as normal.
Had identical GS Auto for 2 years, 25000 miles and never experienced this. All FL2's (3) Gone
2011 Mercedes C180 CGI Gone
FL2 GS Auto SD with heated leather, factory tints, alloy spare and a few other bits.

When a diesel engine turns over and first starts "more so when very could" it may not always fire on the first or second compression stroke. This means that the partly burnt fuel air mixture will be ejected into the exhaust manifold
On the next compression stroke that fires will push the partly burnt fuel vapour in the exhaust system. As these gases pass through the system and on out through tail pipe.
The black smoke you can see on start up is only partly burnt fuel as the engine is trying to start.
This is also more evident when you put your foot down,same sort of thing happens.
The other problem that can happen would be either a new fuel injector not firing properly or a old warn out one, which would leave you in a large black clouds of smoke but would keep pumping it out untill the problem was fixed. If you think its getting worse or is very heavy take the care back and express your concerns

Will be speaking to dealers tomorrow, same result this morning.
Had car at Braemar beginning of month when temp was -16 yes minus 16, when starting display showed "heater plugs on" or something like that, short delay while plugs did their job and engine started without smoke.
Dont think fault anything to do with temperature as it was +7 yesterday ans +8 today.
Possible temp sensor fault telling ECU is at some very low temp but would have thought that behaving correctly at -16 would rule that out. All FL2's (3) Gone
2011 Mercedes C180 CGI Gone
FL2 GS Auto SD with heated leather, factory tints, alloy spare and a few other bits.

Above +5 deg. Celsius the glow plugs don't get energised. A 7-8 deg. is a "just near" temperature.
So, as superspark told you, could be a few strokes without firing because of the low temperatures without "glowing help" and therefore the black smoke.
During time, on all my diesel engines - FL2 included - there are, sometimes, starts with black smoke.
I didn't ever take it seriously as long as once started a few seconds later the engine was ticking properly.

Thanks Alex, understand what you are saying, just that previous FL2 never did this during 24 months.
Same again this morning. Will monitor start up and ambient temp, if still same whem temp is 10+ there is a problem.
Lots of experience (before I retired) with Mondeo 2.0 and 2.2 diesel from 2001 till 2006 and never experienced similar except on 1 car when pump on way out at 2500 miles. This was a known fault and involved new pump, injectors,fuel pipes and tank removal for cleaning. A bearing in pump starting to fail caused minute metal filings to pass through system. Test was to empty fuel filter into clear glass beaker and stand on strong speaker magnet overnight, coating of metal on bottom of glass if fault present. (official Ford procedure) All FL2's (3) Gone
2011 Mercedes C180 CGI Gone
FL2 GS Auto SD with heated leather, factory tints, alloy spare and a few other bits.