Peugeot is developing a 408 GT model which will tackle the Mercedes CLA. The upcoming French car is set to go on sale in 2016 and it will ride on the new EMP2 architecture. Furthermore, it will feature an interior carried over from the new 308, but with more premium materials. 
On the outside, the Peugeot 408 GT will be wider, longer and lower than its 308 sibling and will feature a more aggressive and sporty body kit.
The engine lineup will probably be carried over from the new Peugeot 308 and we must expect to see turbocharged petrol units with displacements from 1.2 to 1.6 liter and outputs carrying from 128 horsepower to 168 horsepower. We also should expect to see the diesel engines. We are talking about the 1.6 and 2.0 liter ones with 118 and 178 horsepower. 
Aside from a 408 GT, Peugeot is also developing a 6008 crossover and a range-topping 608 sedan. Both models are expected to see on the market in 2017.

Source: Peugeot