&gt; Is the thermal envelope really that tight?<p>Not an automotive developer but I&#x27;ve done quite a bit of embedded stuff that was placed in&#x2F;on various items including cars. Yes, it is that tight. You&#x27;re in a sealed container under the hood of a car, the ambient temperatures can be quite high and you&#x27;re not going to be able to dump any of the heat you generate outside of the box you&#x27;re in other than through conduction. Those boxes are typically made of ABS so conduction will be terrible.<p>Of course you could re-design the enclosures, have a heatsink mount point on the outside (some expensive trickery required to do that without breaking the sealed environment), or even an air duct that would allow you to use a fan (but fans tend to fail).<p>So I can totally see why the constraint on power consumption for such an embedded system would be so drastic.