Interesting piece on the Pistonheads site.

Most of the new rules have been introduced to keep up with the number of electronic safety systems on new cars. If there's a warning light you've been trying to ignore for a while, you might want to take a second look at it. Under the new rules, any illuminated malfunction indicator lights for electronic power steering, air bags, seat belt pre-tensioners and the like could mean a failed test.

Other new checks include driver's seat adjustment and defective stability control systems. If a vehicle left the showroom with airbags and seatbelt pre-tensioners fitted as standard, they still need to be present and correct if it's going to pass its test.

This has been a bit of a worry for drivers with cars modified for track use. If you've swapped your airbag-equipped steering wheel for a tasty racing one, fixed your bucket seat in a permanent position and replaced the original seatbelts with a set of harnesses, does that mean a failed MOT?

Probably not, fortunately. A VOSA spokesman has told us that, when the new updates do come in, the inspection manual will include a more thorough definition of modified vehicles in that it will state:

"Where a car has been extensively modified or converted, certain Reasons for Rejection such as 'components missing where fitted as standard' should not be applied, for example:

A car converted for rally use (i.e. rear seats removed and fitted with a roll cage and full harness seatbelts etc) may have been converted so as not to require a brake servo, power steering or airbags.
VOSA says it is expected that modifications to cars converted for track or rally use will be permanent and readily identifiable, and wouldn't include those where an airbag has been disconnected for "occasional" off-road use, for instance.

So it seems like the more modified your vehicle is the easier it becomes to pass the MOT... :-)

Obviously this does not affect a 'Rod' as such, but it's good to know about if you are running harnesses etc in a modified production vehicle.

A couple of 'Extras' to keep an eye on are these.

Electrical Wiring

The condition of a cars wiring will be inspected for damage (such as chaffing against the engine or through an ungrommeted hole etc), and it's security.

Car Battery Security

The battery will be checked for security. This should present few problems unless the wrong sized battery is fitted, the clamp is loose or corrosion has affected support or security of the battery.