spec, in reality will have zero difference. An Elite could easily beat a GLS, considering the youngest 2.5 out there now will be around 11 years old, it will all depend on how its been serviced!
Elite has heavier leather seats, extra heaters in rear seats extra cables and relays to feed heaters, rear blind. bose amp and extra wiring plus more I have probably forgotten. This will make it weigh more than a GLS which does not even have heated front seats so I am told by people one here.
So if the two cars are still at factory spec then the lighter car will be slightly quicker on paper.
I thought you had just finished University.

On paper, maybe. But the youngest 2.5 Omega will be 11 years old. An Elite could easily, easily out drag a 2.5 GLS....
I weigh around 80kg, some people weigh 120kg.... so unless your going really start getting pedantic about drivers weight, amount of petrol in tank, whats in the boot....
Stand by my view, spec, would mean sod-all in 0-60 dash. Its all about maintenance, service history and down to the build of the engine. Some go better than others. Also 99% of it is down to the driver.
Grabbing the paper figures:
2.5 Elite - Minimum kerb weight 1660 kg
2.5 GLS - Minimum kerb weight 1594 kg
So put a fat git in the GLS, and a skinny bugger like me in the Elite, and there is no advantage.