My Drives producing nonsensical records

When I look at precious hour eysenck on My Drives they frequently show absolutely nonsensical records.

For example, today I did a journey of approx. 40 miles but it is showing in My Drives as 4588 miles completed at a speed of 2749 mph.

The route showing on the map appears to go backwards and forwards a huge number of times over the route driven.

Something seems very wrong!