lol.. I'd really like to see what you
racing aficionados are going on to dispute the accuracy of circuits that have been painstakingly recreated in GT4, other than having seen them raced on TV or maybe from having rented a few track-days on Laguna Seca & Infineon. I can tell you what the team at Polyphony Digital is going on--hard data. I found the year-old source that I have been trying to quote (which happens to be none other than
Motor Trend Magazine 
):
"The designers travel around the world collecting the essential data to faithfully reproduce courses and settings. Between 20,000 and 30,000 digital photographs are taken at each facility as the team chronicles every inch to reproduce each tire wall, sign, track wear--even surface friction. Cranes and helicopters are used to offer different vantages, which aid in design and the cinematic game replays. In addition to images, the team conducts a thorough survey with lasers and GPS to chart elevation changes, trace arcs, and record precise linear measurements. Each building, including windows and doors, is measured to ensure true scale reproduction."
The author notes that in total, the team devotes around six months to reproduce each one of the tracks in GT4.
Tell you what, I'll give you Laguna Seca. But you fellas are also second-guessing the accuracy of racing circuits from half-way around world such as Suzuka Circuit and Fuji Speedway in Japan. And the Twin Ring Motegi Road Course, also in Japan, where these guys took more than 150 cars in the Motor Trend article to test them on.
It's a hugely accomplished game, and I don't think Nurburgring and Le Sarthe are the only two accurate circuits in there.
Just some 'fyi'.