Since noone likes to share NASCAR Speedway setups, I'll give out mine that will fairly easily crack 41 seconds at Daytona without drafting and using a controller (sticks). I am a complete noob and just started tinkering, but apparently it is semi difficult to get a car sub-42 seconds at Daytona and I've had many people online wanting my car (for it's setup).
UPDATE: 1-13-2011
CURRENT BEST w/o DRAFTING + TIRE WEAR + FUEL CONSUMPTION: 41.680
TUNER'S NOTES: This is pretty much a specialized tune because it is only useful at Daytona Superspeedway. Racing at Daytona is about four things in this order... 1) drafting 2) handling wrecks/bumps 3) pit strategy 4) solo speed. This thread addresses #4, the shear by yourself lap speed. Solo speed is very important in longer races (i.e. online) where going .01 second faster than an opponent can either let you catch his/her draft, or defend and not allow someone to catch your draft. I'll type more notes at the end of this post.
CAR: 2010 Jimmie Johnson #48 Impala (@892hp/1565kg) Like I said, I'm a noob and I don't know if the different NASCARs have different characteristics.
GT Auto / Maintenance & Service: Oil change... very important
BODY/CHASSIS: Purchase Chassis Reinforcement... very important
-Aero: 20f/40f (lowest settings)
EXHAUST: Titanium Racing (duh)
TRANNY: Fully Customizable (duh)
-Top Speed: 236mph (for no draft running)
-Top Speed: 249mph (for draft running)
DRIVETRAIN: Adjustable LSD
- 60/60/15
SUSPENSION: Full Custom (duh)
-Ride Height: 15f/15r
-Spring Rate: 18.5f/18.5r
-Extension: 8f/6r
-Compression: 8f/6r
-Anti-Roll: 7f/6r
-camber: 4.5f/3.5r
-toe: -0.05f/0.30r
TIRES: Racing Soft (but I may be working on a Racing Hard tune for those pit strategists)
ADVANCED NOTES PREPARE FOR RUN ON SENTENCES AND PARAGRAPHS: It appears that some setting changes have absolutely zero effect on the NASCAR. Spring Rate is suprisingly one of them, but I'm still tinkering. One of my biggest breakthroughs was finding that the car will accelerate quicker, and therefore achieve a higher straight away speed if the camber is set extreme like I have it. Another observation is that changing the camber has zero effect on straightaway tracking (wandering) like it's supposed to in real cars... seems GT5 doesnt have it. If your car tracks, it is tire wear or mechanical damage. It only takes one spin out to ruin a new set of tires. Speaking of needing to pit, these settings actually prefer the added weight of fuel. I have not gotten that deep into testing yet but this may open some doors on pit strategy... i.e. never NOT get fuel.
41 SECOND TIPS: This setup can be touchy, but not as touchy as some of the tunes I've taken from GTP and ran. In fact I've had several tunes with slightly quicker section 1/2 times but turning to the trioval proved too hairy to keep speed. Anyway, these are target speeds for different sections... and remember it takes 3-4 laps to achieve top speed. Honestly If you nail these, you are sub 41.800
START/FINISH/TRIOVAL: 215mph
TURN 1/2: >205 mph... stay low but not too close to yellow stripe
BACKSTRETCH: 220 mph before turn 3/4... key is to ease out wide from turn 1/2
TURN 3/4: >205 mph... stay low again.
Link laps together like this and you will have pretty consistent 41.7XX-41.9XX laps before tire wear and fuel consumption catches you. With even sloppy driving, consistent 42.0XXs are pretty easy, which is why I recommend this tune and not any BETAs I'm working on. This setup is also relatively stable after you run about 20-30 laps to get used to the setup.
Keep in mind 41 second times with this setup are for SOLO DRIVING, cutting to the inside in corners and outside on the straights is a trainwreck waiting to happen with traffic. If you hold your line, either low side or high side, expect a +.200 to be added to your lap times, which are still not that bad for single line races.
ENDURANCE: I've been able to easily pull 41.XXX for at least 10 laps. 42.0XX for at least 15 laps. 15-20 laps I can manage 42.1XX laps. After 20 laps its a pretty steep dropoff, by lap 25 I hover with mid 42's (42.4XX to 42.7XX). Then there is a brick wall and seems that 26 & 27, you are on skates and sliding around near or over the 43 second mark. EXTREME caution must be taken around lap 25 and higher. I would highly advise pitting around lap 25, but keep in mind this is without drafting.
