hi Clint,
If you connect 4 LED's , each with a forward drop of 3.7V, that equals 14.8V.
You cannot do that with a nominal car battery voltage of 12V.
If you connect 3 in series, thats 11.1V total, that would mean if the car alternator was charging at say 14.4V,
you would require a series resistor of 3.3R.
That would drop 3.3V at 1amp.. however if the battery was at 12V, the current thru the LED's would be approx 0.3A.
To be sure of not burning out the 3R3 it would have to be at least 10 Watts for continous or 5Watts for intermittent use.
Do you follow OK.?