I ran the benchmark myself just to see what I get. As I don't notice any FPS dips like that when driving around. I would have to concur with LtMatt. And do wonder if you are noticing stutters while driving with fps dipping to the sub 60 fps?
Not seeing any severe dips to 31 fps @ 4k or 49 fps @3440x1440 21.9 as what my benchmark shows. It was highlighted by various sites and people here when the game first came out that the benchmark wasn't a great reflection of actual gameplay performance.
Just thinking, I didn't even try to play at 4k with no FSR, only attempted the benchmark, silly me Will give that a go later/tomorrow and report back, although a bit pointless really given that at 4k, no GPU has the grunt if you want max settings and high FPS so you'll want to be using FSR/DLSS/NIS tech.