Dan Wheldon acknowledged briefly allowing his mind to wander to four months earlier at the Indianapolis Motor Speedway when the improbable quickly and stunningly became the story complementing the 100th Anniversary Indianapolis 500.Two-time 500 Mile Race winner has a nice ring to it in conversation, and now Wheldon sat on pit lane of the hall of automotive innovation behind the wheel of the next-generation IZOD IndyCar Series that will be one of the storylines of "The Greatest Spectacle in Racing" on Sunday, May 27, 2012."Any time you come to the Indianapolis Motor Speedway is always good, and when you come as the reigning Indianapolis 500 champ, it's special," said Wheldon, who overtook the crumpled car of rookie JR Hildebrand exiting Turn 4 of the final lap to take the checkered flag last May. "The first time I was back here since winning the race I was on the road course, so it's nice to be back on the oval."The occasion was a three-day superspeedway validation session of the Dallara Automobili-built chassis before engine manufacturers begin their testing in earnest Oct. 4-5 at the Mid-Ohio Sports Car Course with drivers Scott Dixon (Honda) and Will Power (Chevrolet) in their own chassis. Teams are scheduled to take delivery of their first chassis in mid-December and commence testing after the first of the year."We'll wait till (Sept. 29) to put the big numbers down," Wheldon said with a smile. "We have to manage our expectations. I know everybody wants to see huge speeds, but it's about doing what's right for the car. This is our final test, and it's important that we learn enough so when the customers get their cars we feel we've given them something they'll be very happy with."Overall, the six weeks of on-track validation with the prototype chassis, working through issues and modifying appendages, has been fruitful and will be beneficial in the long term. INDYCAR Vice President of Technology Will Phillips said the sanctioning body next will work with the manufacturers during their test period of 2.2-liter, turbocharged V-6 engines."We've gone through all the different types of circuits but one (1.5-mile oval, which will be addressed during the manufacturer test phase) and validated the aero configuration against the speed that we intend to have for next year," Phillips said. "It's really been a good collaboration from Bryan Herta Autosport, from Dan and his previous experience and from Dallara."Aerodynamic and mechanical information has been collected into a Dallara "megabook" - a spreadsheet - that will be delivered with base information to teams."It's been very good to be part of the process - to learn about the car, to be at the track and help in the initial testing and development of the car," team co-owner Bryan Herta said. "Some things take a bit getting used to, but I would say this car represents an improvement in almost every area, and that's what we've been doing."It's lighter, safer, faster, and we've worked to validate the mechanical reliability of the car and making sure the way Dallara has designed and engineered the car to perform that the wind tunnel numbers are matching up on track."The program on the 2.5-mile oval also includes a Firestone tire test. Next week, Wheldon will return with three-time Indy 500 champion Helio Castroneves and Graham Rahal for tire testing in the current Honda-powered Dallara "to get a good back-to-back comparison," according to Firestone Racing Senior Project Engineer Dale Harrigle. The 2012 car is lighter, and its oval and road/street aero packages will produce different tendencies than the current chassis."We're doing our due diligence to make sure we don't have any issues," Harrigle said. "We've been working with Dallara and with INDYCAR to confirm the changes to the car, but still nothing beats track testing to make sure we're in good shape for next year's Indy 500."Tire testing will continue on ovals and road courses during the manufacturer test period through mid-December.***2012 Indianapolis 500 ticket orders: The 2012 Indianapolis 500 Mile Race is scheduled for Sunday, May 27. Ticket information can be found at www.imstix.com. Ticket information also can be obtained by calling the Speedway's ticket office, (317) 492-6700 or (800) 822-INDY.