On Mon, 24 Nov 2014 09:27:48 -0800, sm_jamieson wrote:

This year we have a little one to take to the child minders so hectic
mornings, and I have a diesel car which is slower to heat up than a
petrol car. So I was thinking of some type of auxhilliary heater that
can get things going. Any recommendations? - most of the 12V lighter
socket ones seem to have poor reviews.

Since ciggy sockets tend to be fused at 10A, so 120w absolute maximum,
I'm not greatly surprised.

If you want the heater to something quickly, look at Scandi-style plug-in
coolant warmers.

If you really want an auxiliary heater, look at Webasto/Eberspacher-style
diesel-burning ones. Many modern diesels have them as standard, precisely
because the thermal efficiency is good enough that the coolant can take a
while to brew up.