another approach might be to use a thermal camera or IR laser to identify hot spot sources under the hood and to wrap THEM with aerogel...? Here is some info I've found re:automotive uses of aerogel from a cursory google sweep. cheers!

NASA insulation keeps Corvette cool (from SAE article blurb at http://tinyurl.com/n6u67gs )

.... "Recently, the 2014 Chevrolet Corvette Stingray became the first production vehicle to use an aerogel as a lightweight thermal insulation, in this case a sprayed-on coating inside the car’s transmission tunnel. The aerogel, supplied by PaCor Inc. to Tier 1 interior vendors IAC and HP Pelzer, is unmatched in its performance but isn’t inexpensive, said Corvette Chief Engineer Tadge Juechter."

aerogel heatshield with heat rejection stats near bottom of product description:
M7 DFIC Heatshield - www.autopart-performance.com

M7 TESTING:
Control Surface: Aluminum surface heated to a final temp of 440° F.

Test Thermometer: Dwyer Instruments IR 450 non-contact thermometer.

M7 Aerogel Heatshield: After 5 minutes there were no appreciable changes in temperature at the upper surface. So we left the mat baking on the control surface for another 30 minutes. The results: 135° F on the top surface and 440° F on the bottom of the mat! Now that's heat rejection.

three other items were 1) an Aerogel shielded CAI for an M7 (no data given) 2) a fuel rail insulated with Aerogel on a highly mutated VW Golf (no stats) 3) mention of aerogel exhaust heat shielding near turbos to protect adjacent sensitive systems.