Complex sentence: Using the same final drive ratio, the Michigan State Police tests found the 79 St. Regis to be a superior performer than the 400 powered 78 Monaco, in all areas except gas mileage, though performance definitely dropped as drive ratio and engine sizes went down.
Split into simpler sentences: Using the same final drive ratio the Michigan State Police tests found the 79 St. Regis to be a superior performer then the 400 powered 78 Monaco, in all areas except gas mileage. Though performance definitely dropped as drive ratio and engine sizes went down.