Speed/Load/MPG Tests were done on flat straight away sections of the highway. Readouts are from Ultra Gauge.
Vehicle:
1997 Toyota Tacoma 3.4L 4x4 DLX Extended Cab
Testing Protocol:
A-B
Route
62.1 Miles Each Direction
Trip A (Without Topper)
20 Minutes Warmup
Ambient Temp 32f
Intake Temp 56.2
Engine Coolant Temp 192.2
Speed MPG Load RPM
45mph 30.0 28.2 1800
50mph 29.2 28.2 2000
55mph 28.5 29.8 2150
60mph 25.9 32.9 2400
65mph 24.8 34.5 2600
70mph 21.8 38.0 2900
Total trip mpg = 25.0
Trip Average Speed = 53.2mph
Total Time = 1:14
Trip B (With Topper)
Ambient Temp 41f
Intake Temp 70.4
Engine Coolant Temp 192.2
Speed MPG Load RPM
45mph 32.7 26.1 1775
50mph 32.2 26.3 1975
55mph 29.9 28.0 2075
60mph 27.3 31.4 2350
65mph 26.5 32.2 2525
70mph 23.9 35.7 2800
Total trip mpg = 27.3
Trip Average Speed = 53.7mph
Total Time = 1:12
Improvement at 70mph = 2.1mpg
Trip Improvement = 2.3mpg