As Ideo said, its probably about 10-20% (or 3-4k on a 30k vehicle). Where you can do really well is select all the extras you want, and then have them included FOC. Yards make a lot on selling over priced extras - which cost them next to nothing.
Yes, end of month remains the best time - but not right at the end of the month. Probably about the 25th. If they have already hit their targets, they wont be so enthusiastic about doing to much for you. You want them to be close to the target, but not yet over the line. You need to tell them that you "have" to buy a car today because .... It shows that you are serious and will be signing on the bottom line TODAY (really gets their heart pumping those words).
The strongest strategy you have remains this. Right at the death knock, when all is nearly agreed to and the contract drawn up but not signed, just say - "its still too much. I really need to you reduce the price by another X" (and make it a reasonable sum (ie $2k).
The salesperson will 'oo' and 'ahh' and claim this is the best they can do, blah blah blah. And finally I need to check with my manager. He will come back and say "sorry - no can do, this is the best offer we can provide - blah blah blah". At this point, and this is critical stand up. Say thank you and sorry that we couldn't come to an agreement - I will need to keep looking, but we really need to go, as we need a car today...
Standing up is essential, as it removes your 'mental' lock of having to sign this contract.
His world will collapse and he will do one of two things.
1) he will call your bluff and let you walk out.
2) he will run to your manager (this is what you want) and he will come back and knock off another (smaller) amount to what you said you asked for. You then need to decide if this is sufficient.
If he lets you walk, then walk. Just walk out. If he lets you go, you know that you are very close to his critical limit. He is letting the sale go at the price you want it for. Go and have a coffee for 45mins (no less), then call him and say you have found another car, but its not in quite as good condition and you would rather his, if only you could come to an agreement on the price blah blah blah. He will do something for you.
Its now up to you and how patient you are, and if saving a couple of thousand $$ is worth this time and effort. When I was young I used to do this for fun and was always car shopping for friends and family. It was my excitement for a weekend. Now - I just cant be arsed and walk in and say I want this, with these extras, how much - and if I can afford it I take it.
Enjoy.
Blacky
edit - just re-read your post and see that you are financing by novated lease. So some of the above may not be applicable. Cash with no trade in always gives you the strongest position.
