The modest sales spike produced by Britain's scrappage scheme looks pretty tame compared to the chaos that's threatening to overwhelm America's similar 'cash for clunkers' deal.

After just four days the much-vaunted US scheme is reportedly in danger of running out of cash, with the entire $950 million (£575m) of funding that was put into it already spoken for. With thousands of orders already in the system, nobody knows for sure whether there's enough cash left to honour the orders that have already been placed.

The bigger problem is that buyers are still forming queues to order new cars with the rebates, and manufacturer-funded ad campaigns intended to persuade even more to take advantage - you can get up to $4500 (£2700) trading a guzzler against a more fuel efficient vehicle - have barely started to run.

And the US Government is determined that any clunker taken in part-ex is going to be effectively euthanized. Washington is so paranoid about these bangers being broken for parts or resold that it's insisting participating dealers must drain the sump of any clunker they take in before replacing the engine oil with a solution of water and sodium silicate before cranking the engine until it seizes. It's the automotive equivalent of a visit to the gas chamber.