Carl and Jonny's XUD Hillclimber

[cwspellowe]

Plexi windows and tailgate saves a good 20-30kg all in.
Single skin as many panels as you can, just leave the lock/catch mechanisms in place.
Fibreglass bonnet can save about 15-20kg, single skin with a couple of catches to hold it down. Fibreglass is almost as light as carbon and nowhere near the price. Same for the wings and bootlid, fibreglass the lot and look at up to 50kg weight saving.
Presumably you've stripped off the likes of the PAS? Good few kg's there
Lightweight pulleys and flywheel, another 10kg

Depends how hardcore you're going, realistically you could get the car way down at 900kg.