“Come see your local Cadillac dealer today and drive the all new 1975 Cadillac Seville, featuring the revolutionary Cadillac 390cid engine. This all new engine features 4 rotors and develops 265 hp through the use of advanced engine technology and the Cadillac fuel injection system.”
Something with the above sounds odd doesn’t it? Maybe its how much Horsepower the engine makes in 1975? Considering the Seville we did get in 1975 only made around 180hp. Or maybe it’s the fact that the Seville mentioned above didn’t have pistons, but instead had more in common with a 1992 Mazda Cosmo. Even stranger than all of what I've mentioned so far is it could have happened.
This all gets a start in 1969 when George R Elges arrives to become general manager of Cadillac. After a strong 1972 Sales year they found an area that might sell even beater for Cadillac. They had just hired Robert Templin and at the same time noted how well Mercedes was selling entry-level luxury cars. They began to study the Mercedes and why it was selling so well in the United States. This would begin the road towards the 1975 Seville.
By the time 1973 rolled around I am willing to bet they had already selected the Chevy Nova platform as a base. However in the background was probably an even more interesting Seville. At this time GM looks like it had the 1975 or 76 Monza planned for rotary power. Stretch the Monza six inches, widen it three, give it four doors and its own styling and you might have the rotary Seville. More likely was simply plopping the new engine into the nova chassis and doing the Seville’s styling as it ended up with the car we got in 1975.
The rotary engine is already in development, and is almost ready to be deployed into GM and AMC cars. GM bought the license to produce the Wankel rotary engine in 1970 from NSU in 1970 for 50 million. By 1971 two engines have been cooked up and shown to the public in the XP-987GT and a four-rotor vette. The four-rotor engine was making 420bhp whereas the two rotor probably made almost 200 bhp. The engines would be ready as per GM press release by 1975 or 1976. AMC had the Pacer designed around the 2-rotor engine, GM had the Monza and perhaps the Seville ready for the rotary to be installed and sold to the public. Monza would have gotten a similar 2 rotor like the AMC Pacer. The Seville probably would have gotten the 4 rotors.
In 1974 GM postponed the production of the Wankel cars because of emissions problems. Clean emissions are a problem that’s pretty much inherent with the rotary engine. GM couldn’t make the rotary meet the standards of the government with the technology at the time and still maintain a low cost. This sent at the very least Monza and AMC pacer engineers scrambling. The Monza ended up with a variety of piston engines from a four to a 305 v8. AMC went to Audi and bought rights to an Audi 4cyl that sat on an angle not unlike a dodge slant six.
Of coarse, the 1975 Seville came out, pistons and all, as we remember it.