In the market
 

Were you happy with the performance of the S5? If yes, what does it matter how good the RS5 is. As to if it is worth the extra money, as most of us know, the higher you go up in car prices, the less return you will get for the dollar. The RS5 is special car, very limited production. The extra cost is not just for performance but for exclusivities as well. Only you can decide if the extra cost is worth that.
I believe Audi and other Euro manufacturers are still negotiating over the active headlights with the DOT.
I never the drove the new A6 but have own two of the last gen A6, they are not even close the performance of the S5.

Is the RS5 worth the jump from a S5 is really a personal thing. When I started looking for a new car I thought I was set on the S4 but then I saw Audi was going to bring the A/S5 Sportback to the US so moved to being set on the S5 Sportback but didn't want to the first model year so by time the 2018s were getting ready to come out Audi announced the RS5 Sportback which I now have on order. For me I like the looks of the RS5 a lot better than the S5, the extra power and something that was more unique / rare. I could get a S5 and mod it up to get similar looks and power but doing a calculation of the cost it would take to do that made the price difference a non-issue for me to just get the RS5 and have all the feature I like without having to mod. Also no worries about warranty issues by doing power mods to an S5.

Here is a video that might give me a better idea between a S5 and RS5:


I was able to test drive a RS5 Coupe before any RS5 Sportbacks were in stock. They might have let me do that because they knew I was wanting the Sportback or because the Coupe I test drove has been sitting on the lot already for a few months. There is a good chance that any RS5 Sportbacks at a dealer right now have already been pre-sold so they shouldn't be allowing test drives in those.

I think only the new A6 and A7s (maybe the other models that have the new interior design too) can get the Matrix headlights. The Matrix / auto segment dimming will be disabled in the US though due to regulations but it sounds like those regulation might be changing soon so when that happens it sounds like quick software update at the dealer will enable that feature once the rules change.

I personally haven't driven a new A6 so don't really have any input on that. I like the size of my current A6 which the new A/S4 and A/S/RS5s have grown into while the new A6s are now bigger.

I bet if you find a bigger dealer, they might have a test drive RS5 or a manager's demo you can test drive. Tell your current salesman your intention of looking for another dealer who has a RS5 to test drive and I bet he will change his or her tune pretty quickly. Keep in mind the RS5 will have a much lower discount rate than the S5 due to its limited production.

The last I heard, the only customization that can be done to an RS5 is an exclusive color and a Sonoma Green exclusive interior package in the US when I emailed the exclusive program a few months ago.

I bet these Audi dealers have people coming in and asking for a test drive of the RS5 often, you need to convey to the new car manager that you are serious about considering the RS5. Some dealership has varies policies that try to filter out the joy riders. Requiring a refundable down payment and some sort of paper is properly one of those policies. Maybe try to call around different Audi dealerships and ask for a test drive of the RS5, I bet most of them will not just hand you the keys, they will require some sort of commitment.