Not going into your question of how to accelerate, I'll agree with freebeard about installing a coolant heater, assuming you have access to a place to plug it in. No excuses about warm climates - many Ecomodders plug theirs in year-round.
If not an inline coolant heater, then maybe a heating pad that you can stick onto the engine block and/or oilpan?
As these are short trips in a mild climate, then maybe the best way to save fuel would be a bicycle or e-bike?
BTW, have you seen this thread?
SHORT TRIPS? FAST WARM UPS? MPG?
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e·co·mod·ding: the art of turning vehicles into what they should be
What matters is
where you're going, not
how fast.
"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell
[Old] Piwoslaw's Peugeot 307sw modding thread