Herbert holds out for CART drive

The former Stewart, Benetton, Tyrrell, Ligier, Sauber and Lotus driver will test Sigma Autosport's Lola-Ford in August on a road circuit, before he hopes to get his first taste of oval running later in the year.

"The test should be after Chicago [which takes place on July 29]," Herbert told Autosport.com. "It's a photo day, so it's not really a proper test, and it's at Puttnam Park. Then hopefully later on there will be an oval chance."

Sigma is running a single entry for Spain's Oriol Servia this year but Herbert, who is the Arrows F1 team's test driver this year, hopes there might be a chance for him to race in the FedEx-backed series elsewhere.

"I'm still in contact with other teams, so it's just a case of keeping around. I'll be at Portland this weekend, so we'll see," he added.

For a full Johnny Herbert Q&A on his Le Mans 24 Hours exploits, click HERE.