There's been much speculation in recent days of a pending merger between General Motors and Chrysler.

Just how, or why, would that be a good thing?

Certainly Chrysler is in a mess and Cerberus hadn't seen a banking crisis and economic collapse on its radar when it bought the carmaker from Daimler.

But GM has its own problems. A glance at its product portfolio in the USA hints at some age-old brands which it really ought to kill off. Pontiac, GMC or Hummer anyone?

The trend may be for carmakers to ever-broaden their product portfolios, but with that comes some overlap which surely isn't economically sustainable or understandable when the market goes into freefall.

The last thing GM needs is to add yet more niche products to its extensive global range.