Even cruising at high speed in most modern cars is boring (if you're used to older cars anyway) as there is no real sense of speed until 120+ in my experiences , especially if the stretch of track is empty.
Unless there are other cars on track, 120mph was tedious in the Mondeo, even more tedious in the S-Class.
120mph in the MX-5 is boring because you are getting sensory overload from the noise, wind blast, rock hard suspension hammering your spine etc - gets old very fast until you come to the end of the straight...