Scott Dixon leads final Texas IndyCar practice

The New Zealander topped the timing screens with a best lap of 216.139mph, with AJ Foyt's Mike Conway second-quickest at 215.340mph. Running time was cut a few minutes short after Takuma Sato's Rahal Letterman Lanigan car came to a stop on the track.

The session provided the teams with an opportunity to trial a late change to the cars' aero profile for the weekend after concerns from some drivers that too much downforce had been removed in an effort to cut out pack racing.

The series had mandated a maximum rear wing setting of minus five degrees going into the weekend, but after consultation with the drivers, tweaked the rules prior to qualifying to forbid the use of a gurney flap on the rear wing.

While the change proved popular with some drivers, others were concerned that the change was a move too far in the other direction and made the car too unpredictable, leading the series to adopt a compromise solution of permitting the gurney flap to be reintroduced, but stipulating a maximum height of 1/8 inch.

Series officials predicted that the change would return a little more than half of the downforce that had been removed earlier in the day. The cars are still expected to be short of the downforce required to run an entire lap flat.

Pos  Driver               Team/Car                Time      Gap
 1.  Scott Dixon          Ganassi DW12-Honda      24.2344s
 2.  Mike Conway          Foyt DW12-Honda         24.3233s  + 0.0889s
 3.  Alex Tagliani        Herta DW12-Honda        24.3460s  + 0.1116s
 4.  Takuma Sato          Rahal DW12-Honda        24.4161s  + 0.1817s
 5.  Ryan Briscoe         Penske DW12-Chevy       24.4163s  + 0.1819s
 6.  Graham Rahal         Ganassi DW12-Honda      24.4970s  + 0.2626s
 7.  Will Power           Penske DW12-Chevy       24.5481s  + 0.3137s
 8.  Dario Franchitti     Ganassi DW12-Honda      24.5664s  + 0.3320s
 9.  Ed Carpenter         Carpenter DW12-Chevy    24.5839s  + 0.3495s
10.  Josef Newgarden      Fisher DW12-Honda       24.5905s  + 0.3561s
11.  Marco Andretti       Andretti DW12-Chevy     24.6126s  + 0.3782s
12.  EJ Viso              KV DW12-Chevy           24.6412s  + 0.4068s
13.  JR Hildebrand        Panther DW12-Chevy      24.6935s  + 0.4591s
14.  James Hinchcliffe    Andretti DW12-Chevy     24.7121s  + 0.4777s
15.  Ryan Hunter-Reay     Andretti DW12-Chevy     24.7164s  + 0.4820s
16.  Helio Castroneves    Penske DW12-Chevy       24.7260s  + 0.4916s
17.  Charlie Kimball      Ganassi DW12-Honda      24.7745s  + 0.5401s
18.  Justin Wilson        Coyne DW12-Honda        24.7855s  + 0.5511s
19.  Simon Pagenaud       Schmidt DW12-Honda      24.7988s  + 0.5644s
20.  Rubens Barrichello   KV DW12-Chevy           24.8296s  + 0.5952s
21.  James Jakes          Coyne DW12-Honda        24.8822s  + 0.6478s
22.  Tony Kanaan          KV DW12-Chevy           24.8858s  + 0.6514s
23.  Oriol Servia         Panther/DRR DW12-Chevy  24.9654s  + 0.7310s
24.  Katherine Legge      Dragon DW12-Chevy       25.1512s  + 0.9168s
25.  Simona de Silvestro  HVM DW12-Lotus          27.4152s  + 3.1808s