Q on buying a car

[helghast]

im in middle of buying a 1.4 sport corsa b i had a drive in it today. its got a backbox and alloys on it but when i turnt a corner the wheels dug into the arch n rubbed. and the engine light came on. i googled it and it said to check it asap. i want to know is how can i tell if its a genuine 1.4 sport? the reg plate comes up as a 1.4 sport 1999 corsab but me girlfriend thinks its converted or something. ( as its debaged on the boot) is there a way of telling by the papers? would like a answer this week as i love the car and dont want it to be sold. thanks