First, see from the link below, the "year to date figures" (overall sales) of the Ford Focus in the USA are up just over 15%, Honda Civic is up as is the Ford Fusion (on total sales); you are quoting monthly figures and it is coming to Christmas (i.e. money for presents)...this graph shoudl explain:
http://online.wsj.com/mdc/public/page/2_3022-autosales.html
This shows "from a year ago" levels i.e. Toyota sales down 34% while Ford was the lowest at 31%; on this time last year and Ford at 7% down from October with Toyota down 14%..check this out on CNN:
http://money.cnn.com/2008/12/02/news/companies/autosales/?postversion=2008120212
Point notes, Chevy is not Opel and thus even if Opel was nationalised in Germany (which I doubt) it does not matter as it does not effect Chevy; Ellesmere port might not be sold if Opel (which I strongly doubt) is nationalised.
The Chevy Volt has been under development (I think) for about ten years and it is one year from launch in the USA i.e. the tooling is being bought (if not bought); thus I think it is safe to say it is good to go!
I do not see why it requires an engineering section any more than present; typically line workers and production engineers; they have design engineers in the US, they will have designed both hands of drive; thus not from scratch in the UK.
All companies coming to the UK can gain "inward invesment"; if you call up your local RDA (regional development agency) you find it is standard operating procedure; many grants are paid on "job created" and or objecitves acheived, thus there is no gamble with UK tax payers money, if they do not do it, we do not give them anything.
Tesla has very wealthy backers, I think one of the "Google" pair & chap (I think) from Pay Pal; I have every confidence they are fine; they have just secured $£40m USD http://www.teslamotors.com/media/press_room.php?id=1037 and at $100K (I think they are $100K) I do not think people are buying them for the "payback" against oil prices is an issue.
The Chevy Volt does somethign like 150mpg, it will be a reasonable cost, have no raod tax, have high residuals & thus will be an excellent choice for companies/public; it also effectively isolates you from petrol prices (as it uses so little); they are big factors.
The plant will make a high tech car, will employ UK people and will get the UK involved in a car that currently no other manufacturer is coming close; personally I think that is brilliant; on bringing in the jobs alone!...well done mandy! (and well done GM)....so white elephant...no way...I heard people say the same about NaRec in Newcastle....now its "rocking" as a centre of excellence...even the dome came good....O2 arena!