The seven-time world champion came a lowly 10th in this weekend's Australian Grand Prix and he admitted there are a lot of lessons to be learned from his first time behind the wheel for his new team.
Speaking after the race, he said: "It's very tricky, and went a lot worse than I thought that it would go.
"The car was really hard to drive today. So for me, I'm just grateful that I kept it out of the wall, because that's really where it wanted to go most of the time.
"(There was) a lot to take from it. Just getting acclimatized to a new power unit in the wet conditions (and) all the settings that it requires – a different way of driving, a different setup on the steering wheel."
Lewis struggled to get to grips with the wet weather amid mixed messages over the radio and he's vowed to make some changes over the coming days.
He told Sky Sports: "I felt like I was in the deep end today – just everything is new.
“From the first time I was driving this car in the rain, the car was behaving a lot different to what I've experienced in the past, the power unit, all the steering functions - all the things are thrown to you and you're trying to juggle them.
"I didn't have any confidence today in it unfortunately, so I'm going to make some changes next week to the car. Today was the braking and the rear stability, particularly on power - there was lots of snaps, I was nearly in the wall a lot!"