Hi,
well I have a VPS 100 G7 SE just for playing araound a bit with Linux. ( And I don't care about performance on that machine and I won't complain. )
My stats are:
dd if=/dev/zero of=/root/testfile bs=1G count=1 oflag=dsync
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 83.9543 s, 12.8 MB/s
dd if=/dev/zero of=/root/testfile bs=1G count=1 oflag=dsync
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 73.3652 s, 14.6 MB/s
dd if=/dev/zero of=/root/testfile bs=1G count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 62.452 s, 17.2 MB/s
So less disc io compaired to your stats.
As already said, don't expect too much from a low cost vps system. If performance matters to you than you should go with a root-server system.