The latest round of testing of the new Generation 6 model NASCAR Sprint Cup vehicle was seriously cut back after heavy rain hit Concord, North Carolina and Charlotte Motor Speedway all day on Thursday.

The latest pre-season development track session for the Gen-6 cars was meant to be a two-day affair starting on Thursday, but the first day proved to be a complete washout before the heavy rain later later turned to snow and ice.

Although the wet weather had moved away from the region by Friday morning leaving the day with blue skies but very chilly, it still took the facility some time to get the 1.5-mile track into a usable state and as a result cars weren't able to get out for their first runs until shortly after midday. Ice forming inside the SAFER barriers was one reason for the delay, and there were also concerns over 'weepers' which saw water draining from seams in the track.

To try and reclaim some of the lost time, NASCAR arranged to keep the track open through lunch and to allow cars to continue making runs until 7.30pm instead of wrapping at the usual 5pm mark.

Among the 33 drivers attending the test, Roush Fenway Racing's Biffle was the early pacesetter with a lap of 192.601 mph during the afternoon. "This is the first opportunity we've really had to get the car on the race track in the configuration we're actually going to race in," said Biffle

"We needed these two days to really figure out what the car is going to end up like," he added. "We can test into the evening and [hopefully] it won't get too cold, too fast because I'd rather stay as long as we can and get as much information as we can versus having to pack this whole show up and go somewhere else again, or come back later."

The cars got quicker as the temperatures dropped in the winter evening, and Richard Petty Motorsports' Aric Almirola set a new unofficial track record with a laptime of 27.832s (194.021mph) before the session finally ended after around seven hours of test time.

Teams had a three-day test opportunity at Daytona last week, but restrictor plate superspeedways are very different tracks compared with the normal 1.5-mile tracks such as Charlotte that NASCAR more usually races on, so the loss of time this week would have been keenly felt. However the teams, drivers and NASCAR officials were all philosophical about the time lost to the weather delay.

"Testing is valuable, there is no question about it," said Richard Childress Racing's Jeff Burton. "But if we [only get] two hours today, everybody got two hours."

"I think like any test, teams will leave out of here, some will be happy, some will be middle-of-the-road and you'll have a couple of sad ones," said Robin Pemberton, NASCAR's vice president of competition. "They'll continue to work on it."

The test at CMS is the last opportunity for teams to work on their cars out on track before they head to Daytona for Speedweek in February, which culminates in the Daytona 500 season opener to the 2013 NASCAR Sprint Cup championship.

Charlotte Motor Speedway test session times

1. #43 Aric Almirola Ford 27.832s (Leader) 194.021mph (74 laps)
2. #99 Carl Edwards Ford 27.882s (-0.050s) 193.673mph (93 laps)
3. #13 Casey Mears Ford 27.924s (-0.092s) 193.382mph (109 laps)
4. #9 Marcos Ambrose Ford 27.938s (-0.106s) 193.285mph (131 laps)
5. #48 Jimmie Johnson Chevrolet 28.009s (-0.177s) 192.795mph (138 laps)
6. #55 Mark Martin Toyota 28.032s (-0.200s) 192.637mph (97 laps)
7. #16 Greg Biffle Ford 28.036s (-0.204s) 192.610mph (92 laps)
8. #56 Martin Truex Jr. Toyota 28.063s (-0.231s) 192.424mph (94 laps)
9. #15 Clint Bowyer Toyota 28.070s (-0.238s) 192.376mph (109 laps)
10. #17 Ricky Stenhouse Jr. Ford 28.075s (-0.243s) 192.342mph (131 laps)
11. #42 Juan Montoya Chevrolet 28.092s (-0.260s) 192.226mph (85 laps)
12. #5 Kasey Kahne Chevrolet 28.095s (-0.263s) 192.205mph (101 laps)
13. #20 Matt Kenseth Toyota 28.104s (-0.272s) 192.143mph (92 laps)
14. #29 Kevin Harvick Chevrolet 28.108s (-0.276s) 192.116mph (121 laps)
15. #22 Joey Logano Ford 28.123s (-0.291s) 192.014mph (139 laps)
16. #14 Tony Stewart Chevrolet 28.134s (-0.302s) 191.939mph (70 laps)
17. #18 Kyle Busch Toyota 28.158s (-0.326s) 191.775mph (156 laps)
18. #78 Kurt Busch Chevrolet 28.172s (-0.340s) 191.680mph (67 laps)
19. #88 Dale Earnhardt Jr. Chevrolet 28.194s (-0.362s) 191.530mph (97 laps)
20. #39 Ryan Newman Chevrolet 28.196s (-0.364s) 191.517mph (66 laps)
21. #1 Jamie McMurray Chevrolet 28.214s (-0.382s) 191.394mph (79 laps)
22. #24 Jeff Gordon Chevrolet 28.216s (-0.384s) 191.381mph (62 laps)
23. #31 Jeff Burton Chevrolet 28.241s (-0.409s) 191.211mph (97 laps)
24. #21 Trevor Bayne Ford 28.278s (-0.446s) 190.961mph (122 laps)
25. #11 Michael McDowell Toyota 28.315s (-0.483s) 190.712mph (204 laps)
26. #30 David Stremme Toyota 28.332s (-0.500s) 190.712mph (80 laps)
27. #10 Danica Patrick Chevrolet 28.342s (-0.510s) 190.530mph (114 laps)
28. #2 Brad Keselowski Ford 28.355s (-0.523s) 190.443mph (96 laps)
29. #47 Bobby Labonte Toyota 28.468s (-0.636s) 189.687mph (46 laps)
30. #27 Paul Menard Chevrolet 28.469s (-0.637s) 189.680mph (107 laps)
31. #7 Dave Blaney Chevrolet 28.645s (-0.813s) 188.515mph (64 laps)
32. #34 David Ragan Ford 28.752s (-0.920s) 187.813mph (96 laps)
33. #34 Scott Speed Ford 28.882s (-1.050s) 186.968mph (41 laps)