mk1 172 - early models have lightweight ally bonnet. Longer gearing that the mk2 models. Later mk1s dont have a functioning gear change light. Weigh about 1035kg
mk2 172 - Loads of toys like auto wipers, xenon lights, later models have traction control. Weigh about 1110kg. Shorter gearing to compensate for the extra weight. Some revisions to air intake/airbox.
m2 172 Cup - stripped out version of mk2 172. Weighs about 1021kg. No spare wheel, lighter glass, no toys, no leather, revised suspension. Believe it has the same gearbox as the mk2 172.
None of them say 172 on the back. Cups says 172 on the side door pillars. All have loads of niggley faults associated with them. All great fun. Bargins to be had with early low mileage mk1s (should be able to get them for less than £8k now). Cups can be had new for about £11k and MK2 172s new for about £12k.
Rhys