That's a good question but from my experience it's not the case. I live in France and 20 to 30 years ago, after hours driving on highways, it was quite common to have your car plastered with bugs.

Now it rarely happens.

And with the last 2 cars I've had, I know it's not an aerodynamic issue because one of my hobbies is to do track days.

I go to Michelin's wet track something like once a year and it's bugs' paradise: fields, grass all around and very humid because the track is wet so you can hydroplane easily. Bottom line is my car gets plastered there and we don't even drive that fast (something like 80/90 km/h or 50/55 mph).

I drive a jeep (basically a brick on wheels) and bugs are still awful.

The reason I asked this question was because I drive a Nissan Cube.

Do you see a lot of bugs?

Yes.

But were they as bad as they were?

I've had similar experience with bikes on a roof rack, where there's not a significant change in aerodynamics over the time.