  We present the results of XMM-Newton observations of two AM CVn systems -
V396 Hya and SDSS J1240-01. Both systems are detected in X-rays and in the UV:
neither shows coherent variability in their light curves. We compare the rms
variability of the X-ray and UV power spectra of these sources with other AM
CVn systems. Apart from ES Cet, AM CVn sources are not strongly variable in
X-rays, while in the UV the degree of variability is related to the systems
apparent brightness. The X-ray spectra of V396 Hya and SDSS J1240-01 show
highly non-solar abundances, requiring enhanced nitrogen to obtain good fits.
We compare the UV and X-ray luminosities for 7 AM CVn systems using recent
distances. We find that the X-ray luminosity is not strongly dependent upon
orbital period. However, the UV luminosity is highly correlated with orbital
period with the UV luminosity decreasing with increasing orbital period. We
expect that this is due to the accretion disk making an increasingly strong
contribution to the UV emission at shorter periods. The implied luminosities
are in remarkably good agreement with predictions.
