[beng-1]

Here is what I found :

Z28 Performance Test Data
Source: Car & Driver - 9/73: Test Vehicle: 1973 Type LT Z28/RS, 4 speed, 3.42:1
Gear Ratio MPH/1000 Max. Test Speed
1 2.52 8.7 52 mph @ 6000 rpm
2 1.88 11.6 70 mph @ 6000 rpm
3 1.46 15.0 90 mph @ 6000 rpm
4 1.00 21.9 123 mpg @ 5600 rpm
Standing 1/4 mile: 15.2 sec. @ 94.6 mph
Top Speed (Observed) 123 mph
70 - 0 mph 192 ft. (0.85G)
Fuel Milage: 10.0 - 13.5 mpg/regular fuel
Cruising Range: 180 - 240 miles
Interior sound level: 76 (dBA) / 70 mph cruise, 85 (dBA)/ full throttle