Cadillac’s quest to make the new ATS sports sedan a formidable rival for the BMW 3 Series is turning into a severe case of OCD. We knew they’ve been testing the car over and over at the Nurburgring, but as we get closer to the car’s launch in summer, they reveal more details about the development process. This time they tell us about their efforts to keep the weight of the car down, making it the lightest in this segment.

They’ve gone to enormous length with weight saving tricks and lightweight materials, but they’re still not sure it they’ve puled it off. Cadillac say the ATS may be the lightest in its segment! The ATS has a curb weight less than 3,400 pounds (about 1,500 kg). We guess they’re alright here.

By keeping the weight down not only you enhance the handling, it also helps the fuel consumption and performance. So the aluminum hood and magnesium engine mounts in the ATS are indirectly contribute to its 30mpg fuel economy.

Weirdly though, Cadillac believes the best way to save weight is ditching as much aluminum as they can. ATS benefits from cast iron in the rear differential instead of aluminum, specially engineered straight steel links in rear suspension with lightening holes instead of using aluminum, and an acoustically laminated windshield and side windows that are lighter than standard tempered glass.

This is the best they could do without sacrificing the car’s comfort an dynamics. Great stuff for a 34 grand sedan.