hi, i finally took my 94 sls in to get the freeze plugs changed out. ive had a coolant leak and that terrible smell for about a year and in the last month it started to burn so bad that it steamed up through all the cracks in my hood and stunk sooooo bad. i asked the gm/caddy place how much it would cost to have it done and he said 'anywhere from 1500-2000 dollars'! holy crap, so i decided to let the local shop do it and i must say, no smell at all. it was indeed the freeze plugs that were leaking on the exhaust. i was shown the location (after my transmission was on the floor) and it was a very difficult place to get to making it necessary to take the tranny out. so, all in all....i solved the problem paying 4 dollars for freezeplugs and 550 for labor. also had swaybars, seals, etc put in taking the total to 850, but still a far cry from what the dealership wanted.

so, to make a long story short, if you smell coolant or have a leak, check the freeze plugs (yes, the nstar does have them). hope it helps somebody.