Le Mans 24 Hours Rubens Barrichello has revealed he is hitting faster speeds driving his Dallara-constructed LMP2 prototype than he did during his final year of Formula 1, but admits it is why his car is otherwise slow on the timesheets.

The 11-time F1 race winner, who retired from the series at the end of the 2011 season after a record-breaking 322 starts, is making his Le Mans 24 Hours debut this weekend at the age of 45 with the Racing Team Nederland in the LMP2 class.

Paired with 1988 Le Mans 24 Hours winner Jan Lammers and Frits Van Eerd, Barrichello's team is one of 25 gunning for the LMP2 title this year but does so driving the lesser-used Dallara P217 chassis in a field dominated by the Oreca prototype both in terms of numbers (14) and pace.

Debuting in the year that sees LMP2 regulations tweaked to make them faster in a straight line, Barrichello says he was shocked to be hitting 340km/h (210mph) on the Mulsanne straight and had to check with the team if this was correct on his first laps.

"When I first drove the car I radioed in and said: "Is the... blue light close to the limiter in sixth gear?" They said yes, so I thought to myself either we have very low downforce, or we have superpowers! We were going at around 340 kph, and I don't think I reached that in my last race in Formula One."

However, with the team approximately three seconds per lap down on the best Oreca cars in LMP2, Barrichello admits the searing pace down the straights is ultimately losing it too much time due to the trade-off in poor handling.

"It was a big gap - more than three seconds difference I think. My own lap was competitive - I felt good in the car. I am used to driving the Stock Cars right now, but the formulas are still in my mind. There are rules and we have packages and certain things we have to follow, and we will try to mix different combinations to see if things get better, especially because it's supposed to be very hot.

"The car was actually well balanced...there was nothing bad. But the reason we are three seconds away is that we were a little too fast on the straights and not fast enough in the corners.

Oreca-built LMP2 entries dominated first qualifying around the Circuit de la Sarthe filling the top 12 positions, with Barrichello's car the best-placed non-Oreca in 13th and five seconds slower per lap.

Dallara, Ligier and Riley are the other variants of LMP2 competing this weekend, but all three have struggled to match the pace of their French counterparts.