Three-point-seven miles and seventeen turns demanding constant concentration. Even on the straights you have to stay alert for one of the other 30-odd cars on the track. All while trying to focus through the infamous lumps and bumps.

Used to that?

Then try doing it at night.

Endurance racing is like nothing else in motorsport and, as ever, the endurance year kicks off with the 12 Hours of Sebring on March 20.

The race forms the first round of the American Le Mans Series. However, the race also welcomes teams from all over the world, who come to America simply for the event, drawn in by the prestige of winning at Sebring and the chance to run their cars after the winter.

That category is somewhat depleted compared to recent years. Audi have opted to develop their new R15-plus car away from the cauldron of competition, though Sebring remains one of the tracks they plan to test on. That decision leaves the two 908 coupes entered by reigning Le Mans 24 Hours champions Peugeot as the only diesels on the grid, though they epitomise the team who use Sebring as an extended test, team principal Olivier Quesnel stating earlier this week they a Sebring entry was mainly “in order to put the team in a “race” situation”, as well as testing the car itself over that surface.

Peugeot will headline the premier LMP1 class of only five cars, after the withdrawal of Creation Autosportif and Intersport Racing, the latter after driver Jon Field suffered a massive accident in testing. Though Field was uninjured, the car was destroyed, the team now focusing on their LMP Challenge car and preparing the Lola P1 car for the second round of the series at Long Beach.

That decision points at the biggest change to the race for 2010, with the addition of two extra classes compared to last year's race (though LMGT1 continues to be omitted from the ALMS).

For the first time the LMP Challenge class will line up in the series. The class uses the same spec FLM09 chassis that appeared in Formula Le Mans in Europe last year, with six entrants expected to take the green flag. Returning this year, for a full season is the GT Challenge class – after debuting as simply the 'challenge' class in 2009. The class features GT3 Porsches (though theoretically it is open to any similar spec  car), the seven entrants for Sebring, like their LMPC brethren encompassing both recognized teams and drivers, gentlemen drivers and young drivers entering at the lowest level of the series.

While it may be Peugeot's race to lose at the front there are signs of close races thoughout the field, none closer than in the 13 car field of GT2.

The class, by far the biggest at Sebring this year sees factory assisted efforts by five different manufacturers. Where as the best prototype teams visit the US simply for Sebring, America is the home to the best GT2 teams in racing.

Risi Competizione Ferrari's alone account for the last two class wins at Le Mans, and even they will face competition from Ferrari newboys in Extreme Speed Motorsports. With Flying Lizard leading the Porsche charge and Corvette Motorsports making their GT2 Sebring bow (two teams with definite previous after the violent end to 2009) a pair of BMWs and another Sebring debut for JaguarRSR, and you have the makings of a classic.

The 58th running of the 12 Hours of Sebring gets underway at 10:30am local time (2:30pm UK) and will be broadcast live on Speed in the U.S. and MotorsTV in the UK. You can download a Spotter Guide from Andy Blackmore Design here.

Live flag-to-flag commentary is also available from Radio Le Mans both at Sebring itself and through satellite radio and the internet. You can read more about their coverage for Sebring and beyond here.

Photo credit: Peugeot media