How fast is that Cadillac?

By most accounts the 92-97 Seville cars are marginally better than the 98 and later from an aero standpoint....just very slightly. Wind noise, styling, cooling, ride height, etc. all factor into the aero numbers. There was no conscious effort to make it "worse" for drag as a lot of the aero features are better. It is probably the rear end treatment on the earlier cars that make them a little better. Keep in mind here that we are only talking a tiny difference so don't rush out and sell a later car to get "better" aero....but if you're shooting for 200+ at Bonneville get a 95....

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I've heard a few times the 92-97 cars have "better" aerodynamics than the 98+ cars do. Is this the case? The 92-97 seems "boxier" or "edgier" and I'm surprised it creates less drag, if it does. Why did they move to a new design that performed worse in aerodynamics tests? Was it purely from a styling standpoint?

--Jason

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As a reference point I once ran 6 randomly selected 98 STS cars for top speed. The cars were tested on a 5 mile circular, banked track so there was little or no side load evident. The cars were run for 15 miles at WOT to ensure that they were stabilized. Top speed readings were taken at 4 points on the track to average out wind influences. The cars were run on normal pump gas premium and the ambient temperature was about 90 degrees. The average top speed of the 6 cars was about 146 MPH. They were actually very closely grouped in terms of top speed with differences in the wind causing much more variability at the different points on the track. These were perfectly stock production vehicles. My suspicion is that higher reported top speeds are due to grade (down hill), wind (tailwind), cooler ambient conditions, etc. Typically I would expect the 95 model sevilles to run a few miles per hour faster due to the power output of that generation of engine and the aerodynamics of that body....but that is just a casual observation...not a tested, proven fact.

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Probably your car is electronically limited to 155 mph.

Otherwise with 300 hp would do just over that; the cartest simulation suggests it would take a lot more hp to push the overdrive 4th gear much higher than 157 mph, and 3rd runs out at 140 mph. I have heard one claim of 161 mph, but I think they were optimistic.

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I was on a long copless road I was going 70 mph I put in 3rd and floored it it shifted in to 4th at 121 mph I pushed it to 141 mph at 5600 rpm and I let off. I have air box mod, mass screen removed,3" after res to Y pipe.How fast can this car go? I also have 18"wheels with 245/45/18/ZR tires it felt great!!