In this case, how does Tesla handle change fees? Imagine some of the option groups are reconfigured and the base price of the car goes up.
Historically, Tesla has used the notion of "old pricing" and "new pricing". When "new pricing" is announced (either at a press release or Design Studio, or both), customers that haven't yet taken delivery are generally bucketed into three groups:
1. already configured but not delivered
2. "in the middle of configuring"
3. haven't configured yet
By default, group 1 gets the old pricing (that they configured with). Some customers try to "call Tesla back" and request the new options and pricing. The answer is usually one of: (a) too late it's already too far in the production queue, (b) you can change it with a $500 change fee for X more days, or (c) you can change it for free for Y more days.
Group 2 has access to both old and new pricing for a limited time with no penalty. After that time passes, only new pricing is available.
Group 3 only has access to the new pricing.
At least that's my recollection and summation of the pattern I've seen since late 2012.