Whenever someone brings up a coupe that's just a two-door version of an existing sedan, my impulse is to immediately criticize the vehicle and then make snap judgements about the life choices of anyone who's bought one. They are completely useless. I love impractical, useless cars. We all do. In a performance car, sacrifices must be made. Back seats? Toss them. Trunkspace? It had to go. But I'm not talking about performance cars here. I'm talking about the coupes made when a car company takes an existing four-door, and turns it into a coupe. It's a recipe for...something bland that I've already forgotten the name and taste of.
They just give up too much practicality, and for what? You have a car with the same wheelbase as the sedan, with the same weight as the sedan, lugging around the same backseats as the sedan, but you can't access those seats without getting out and sliding the front seats forward. It's maddening.
I'm told in some cases, there may be a slight performance benefit: the chassis may be a bit stiffer. But this doesn't count. The person buying an Accord Coupe is not going to notice a 4% rigidity gain over the regular Accord.
Is it always terrible? Yes. But sometimes it's not quite as objectionable. A car that uses the coupe shape to embrace a bolder aesthetic, and takes the design to new heights where the sedan could't go — that's justified. It's rare, and I'm talking almost exclusively about the Cadillac CTS Coupe. The rest of them mostly look like weird, disproportionate clones of the sedans.
Here's where it's more vague: I find Mercedes E and C Class coupes to be dreadful, but the larger, more extravagant CL is brilliant. It is, for lack of a better word, elegance. There is something to be said for a car that is longer and bigger than it needs to be, just because it can. True grand touring, with room for the driver and his or her guest. I get that from the CL. I see that in the Audi A5. But that aspect doesn't shine through as much in an Altima Coupe. There's a style barrier, or at least a price barrier, and the majority of these cars are trapped on the wrong side of it.
The lesson? If there must be a coupe version built on a sedan, make it a striking, daring development of the sedan's design that goes further. Give it it's own identity, apart from the sedan. Offer a performance version only offered for the coupe. And if a company follows all of these guidelines, it will still probably be milquetoast.