This technology is already created and can save thousands of lives. The system will determine the amount of alcohol in the drivers blood in less than a second. All this does is make sure intoxicated people cant break the law and drive. If you don't plan on driving drunk, then this shouldn't be an issue for you.
The argument that this won't affect people who don't drive drunk doesn't hold much water.
The additional manufacturing, repair, and inspection costs will be passed on to consumers. This will easily add up to several hundred or even thousands of dollars over the life of the vehicle. This is effectively punishing all drivers for a crime committed by a small minority of them.
There is always the risk of false positives (or false negatives, for that matter.) Just imagine running late for work and your car refusing to start because it doesn't like your mouthwash or hand sanitizer.
The extra 10+ seconds (and taking off your gloves in the winter) required to start your car will slowly grate on your nerves. Not to mention it could be dangerous if, for example, your car stalls on the highway and you have to take a test while in motion to get it started again.
I also have to wonder how effective these tests will even be. For example, what's stopping you from drinking after you start the car? Is it going to continuously test you as you drive? And what is it going to do if you fail? Shut the car off on you while you're in motion?