Mazda 3 = 155 horsepower and a curb weight of 2,950 pounds?
If you drove mazda 6, it's hard for you satisfy with 155hp at 3k lb Mazda 3? It's like a 8+ second car, you can't pass anyone unless you have to floor the gas pedal to the ground to make a slow pass on a highway.
Why not get a new Mazda GS-V6?
If you mind the gas usage and don't mind people(who have no idea about cars) look at your differently if you drive a korean car, then take a look at the Hyundai Sonata 2.0t.
I bought one about 1.5 months ago, I am getting 8.9L/100KM currently. That's for a 274HP @ 6,000 rpm and 269 lb.ft @ 1,750-4,500 rpm car. Almost the same fuel efficiency as my gf's matrix, but double the hp and torque.