I got the upgrade bug when I was in the dealer getting some Audi service done on my wagon.
They had an Atlas Grey (favorite color) Cayman (base) 07 for a pretty good discount.
I waited until today and went in and took it for an hour demo.
Impressions:
I like the interior/room of the 987. The high roof made the Cayman feel quite roomy.
While it has more power, it didn't feel any faster than my base 986 Boxster. At times it felt more stiffly sprung but other times it felt much easier to drive (easier clutch, lighter steering, less abrupt brakes). The hatch captures a lot of the engine noise which is both good and bad. The handling was great - it felt more planted than my Box in tight turns.
Overall, there wasn't enough "Wow" to justify the trade. The discount isn't that great (13.5% on an 07 -- I was looking for more like 16-17%) and the trade offer was low. In short, I'm sticking with the Box for now. Maybe a Cayman S is in my future????
