LA LA singer Simpson took a 30 mile (48 kilometre) drive out of Los Angeles with her assistant last week (08FEB05) just to meet up with the THAT 70S SHOW star on the desert set of his new movie LA MUERTO.
And, after hugging and holding hands for 30 minutes, the couple disappeared into Valderrama's trailer to enjoy a midnight feast of burgers and fries.
A set spy says, "There was no kissing but the way they greeted each other and then cuddled, there was no mistaking that Wilmer and Ashlee are more than just buddies.
"Why else would someone drive all the way out of LA in the middle of the night to join someone unless there was more to it than just a friendly visit."
Valderrama has been single since splitting from Lohan last October (04) and Simpson has been keen to play down her on-off romance with pop star RYAN CABRERA.