The cars being "manufactured are made for foreign owned companies and afaik, assembled mostly from imported parts,so although beneficial to the economy,not as much as you might think.
Its only right that a modern,civilised, (formerly) wealthy country should have sensible levels of pey,health & safety,employment rights,benifits etc. but we have (yet again) thrown the baby out with the bathwater and made it very difficult for British business to be competitive. I listened to a debate/phone in on the radio recently where many listeners called in to say how strongly they believed the Govt. should legislate for workers to have time of with pay to grieve the loss of a pet !! I had to check it wasnt the 1st of April ffs.
Its now common (and possibly a legal requirement ?) for people who become sick during holidays from work,to claim sick pay and have the days they were sick added back on to their holiday entitlement - fackin ludicrous imo.

And as Kevin mentioned,we are tied and trussed up by EU red tape,which for some reason seems to apply much more in this country than most others.
We are still quite succesful at high end engineering,and hi tech stuff though. F1 and motorsport technology and manufacturing in general is centred in the UK,and Cambridge seems to be becoming our silicon valley,with companies such as ARM technologies doing very well indeed,so its not all doom & gloom.