Mileage test for my 94 Ford Range 2.3L 
%Change Miles Gallons MPG
N/A Average 265.11 11.79 22.41 No O2 sensor
2.67% Average 282.84 12.28 23.01 O2 sensor installed
9.21% Average 302.92 12.07 25.13 CAI mod
Date Odometer Miles Gallons MPG %Change Notes:
1 11/24/08 252412.2 342.6 14.470 23.68 n/a Baseline Data - Burned out O2 sensor
2 12/01/08 252696.8 284.6 12.188 23.35 -1.38%  
3 12/10/08 252973.2 276.4 12.033 22.97 -1.63%  
4 12/17/08 253250.3 277.1 12.744 21.74 -5.34%  
5 12/23/08 253517.1 266.8 11.473 23.25 6.95%  
6 01/02/09 253779.7 262.6 11.798 22.26 -4.29%  
7 01/07/09 254033.5 253.8 11.586 21.91 -1.58%  
8 01/15/09 254368.6 335.1 14.701 22.79 4.06%  
9 01/19/09 254512.3 143.7 7.298 19.69 -13.62%  
10 01/22/09 254768.0 255.7 11.262 22.70 15.31%  
11 01/29/09 255070.7 302.7 13.940 21.71 -4.36%  
12 02/04/09 255300.8 230.1 10.403 22.12 1.86%  
13 02/09/09 255529.5 228.7 9.849 23.22 4.98%  
14 02/16/09 255781.1 251.6 11.279 22.31 -3.93%  
1 02/19/09 256016.2 235.1 10.250 22.94 2.82% Replaced O2 sensor.
2 02/26/09 256332.3 316.1 13.547 23.33 1.73%  
3 03/04/09 256562.9 230.6 10.203 22.60 -3.14%  
4 03/09/09 256819.9 257.0 11.410 22.52 -0.34%  
5 03/16/09 257089.1 269.2 11.828 22.76 1.05%  
6 03/21/09 257348.5 259.4 11.230 23.10 1.49%  
7 03/27/09 257639.0 290.5 12.608 23.04 -0.25%  
8 04/02/09 257909.1 270.1 11.908 22.68 -1.56%  
9 04/07/09 258162.9 253.8 11.176 22.71 0.12%  
10 04/14/09 258485.7 322.8 13.824 23.35 2.82%  
11 04/21/09 258771.6 285.9 12.583 22.72 -2.70%  
12 04/27/09 259048.1 276.5 12.048 22.95 1.01%  
13 05/03/09 259387.9 339.8 14.259 23.83 3.84%  
14 05/18/09 259740.9 353.0 14.984 23.56 -1.14%  
Starting Mileage 262140.8
1 07/09/09 262424.3 283.5 11.310 25.07 8.94% CAI Mod - Removed restrictions 23.01
2 07/16/09 262694.8 270.5 11.184 24.19 5.11%   23.01
3 07/22/09 262953.9 259.1 11.021 23.51 2.17%   23.01
4 07/29/09 263212.5 258.6 11.124 23.25 1.03% I replaced the fuel filter 23.01
5 08/03/09 263441.9 229.4 9.819 23.36 1.53%   23.01
6 08/07/09 263713.4 271.5 11.250 24.13 4.88%   23.01
7 08/17/09 264080.5 367.1 15.667 23.43 1.83%   23.01
8 08/21/09 264345.9 265.4 11.163 23.77 3.32%   23.01
9 08/26/09 264580.0 234.1 9.980 23.46 1.94% new FPR installed 23.01
10 09/01/09 264817.8 237.8 9.760 24.36 5.89%   23.01
11 09/09/09 265102.1 284.3 11.690 24.32 5.69%   23.01
12 09/14/09 265370.7 268.6 11.212 23.96 4.11%   23.01
13 09/18/09 265640.3 269.6 11.169 24.14 4.90%   23.01
14 09/23/09 265922.1 281.8 11.761 23.96 4.13%   23.01
15 01/18/10 269259.1 307.3 12.481 24.62 7.00%   23.01
16 01/25/10 269560.4 301.3 12.519 24.07 4.60%   23.01
17 02/01/10 269828.9 268.5 11.468 23.41 1.75%   23.01
18 02/05/10 270078.4 249.5 10.663 23.40 1.69%   23.01
19 02/11/10 270368.9 290.5 13.073 22.22 -3.43%   23.01
20 02/17/10 270628.5 259.6 11.355 22.86 -0.64%   23.01
21 02/23/10 270926.7 298.2 12.388 24.07 4.61%   23.01
22 03/02/10 271254.2 327.5 13.675 23.95 4.08%   23.01
23 03/08/10 271607.6 353.4 14.706 24.03 4.44%   23.01
24 03/15/10 271922.5 314.9 12.783 24.63 7.06%   23.01
25 03/18/10 272187.3 264.8 10.940 24.20 5.19%   23.01
26 03/30/10 272517.6 330.3 13.303 24.83 7.91%   23.01
27 04/06/10 272791.7 274.1 10.761 25.47 10.70%   23.01
28 04/12/10 273047.5 255.8 10.203 25.07 8.96%   23.01
29 04/16/10 273324.2 276.7 10.930 25.32 10.02%   23.01
30 04/23/10 273641.7 317.5 12.692 25.02 8.72%   23.01
31 04/30/10 273979.7 338.0 12.971 26.06 13.25%   23.01
32 05/06/10 274242.6 262.9 10.611 24.78 7.68%   23.01
33 05/20/10 274525.7 283.1 10.910 25.95 12.77%   23.01
34 05/26/10 274836.4 310.7 11.994 25.90 12.58%   23.01
35 06/07/10 275151.6 315.2 12.682 24.85 8.01%   23.01
36 06/15/10 275486.9 335.3 12.834 26.13 13.54%   23.01
37 06/22/10 275801.5 314.6 12.315 25.55 11.02%   23.01
38 06/28/10 276071.3 269.8 10.561 25.55 11.02%   23.01
39 07/05/10 276384.0 312.7 12.017 26.02 13.09%   23.01
40               23.01
41               23.01
42               23.01