I never said anything wrong about platform sharing. Its when you rebadge your almost all your products at least 3 times in 6 tiers, none of the products are unique and all the products starts to canabalize itself.

The difference between a Accord and TL/CL is that there's more to the difference than just slap on different cosmetics and slight powertrain tweaking. The Accord and TL/CL has different displacement, different size, different price point range. Accord's price ends at around $28k, while the TL starts at around $28k. Same formula with the Civic/RSX.

Now look at GM. Take the W-body platform of the Grand Prix, Regal, Century, and Impala. All are basically same size, same engine displacement, and same $20k-28k range. I have 3 choices to pick if I was looking at $25k and 200hp between them. Same problem goes for the GM Trailblazer and its twins, Cavalier/Sunfire (soon to be added ION when the next Cav comes), Malibu/Alero/Grand Am.

Even if Honda and most other automake rebadge models, they separate the brand and pricepoints a lot further than GM. Honda Pilot EX leather navi is $33k. The base Pilot starts at $36k.

The Solstice is a very nice little roadster, but the awe of it WILL be deluted with 2 rebadge that WILL overlap in price. Plus, roadsters are small volume seller and having 3 brand/dealer selling near the same version of that roadster is just extra overhead.