NEW YORK (TheStreet) -- The Subaru Forester is one of the aces in Subaru's great success story in terms of U.S. sales. Subaru sold 513,693 cars in the U.S. in 2014, up 21% from 2013. To put it in perspective, that's 30-times Tesla's (TSLA) 2014 unit sales in the U.S., which were flat over 2013.

Forester is Subaru's best-selling model in the U.S., with 159,953 sold in the in 2014, up a whopping 29% over 2013. Unfortunately, the current model of the car has a fatal flaw: the infotainment system.

There are bad infotainment systems on the market that are nevertheless usable because they at least provide the most basic ability to connect with smartphone via Bluetooth. Not so with this Subaru. It failed even the most basic test, playing podcasts in the car.

It doesn't connect the Bluetooth at all with some smartphones. Running Google's (GOOG) (GOOGL) reference phone, the Nexus 5, on the latest software, Android 5.1 didn't work at all. Trying two of them, the system refused to pair Bluetooth, on any level, at any time.

The initial Bluetooth pairing worked with a couple of other phones, including a Samsung (SSNLF) Galaxy S5 running the considerably older Android 4.4.2. An old Apple (AAPL) iPhone also worked for the initial Bluetooth pairing.

However, the system appears to only enable one phone to be paired at the same time. You have to delete one profile, before you can add another one. That's absolutely crazy. It's like saying that you can only have one key to your house.

Even worse, even if you had only one phone, the Subaru infotainment system didn't appear to be re-pair once you turn on the ignition again. Perhaps human error accounted for this last issue, but it wouldn't re-pair without deleting the Bluetooth profile and starting up the process from scratch. That's obviously a non-starter.

It's worth mentioning all sorts of other aspects of the Subaru Forester, but it's impossible to get beyond this total Bluetooth failure. This is a feature that's mission-critical to new cars, and it must work with every phone, all the time, flawlessly. Anything else is unacceptable.

On the plus side, the Forester looks decent, especially in this most recent version. It's got an "honest" look to it, rugged and practical. The doors open big and wide. It's easy to get in and out. The interior space is reasonably generous and very practical.

The engine-transmission combination works well. Many automotive enthusiasts and journalists don't like CVTs (continuously variable transmissions) but they are very rational. The power delivery is smooth, even though the engine noise is on the somewhat loud and cheap side.

The steering wheel is among the cheapest and nastiest plastic ones I've experienced in years. It's cheap and slippery. The driver's seat is not good, although not the worst to come out in the past year. (That low point came in the Chevrolet (GM) Spark.) It's just too soft and squishy. Like the steering wheel, feels cheap. The seating position is reasonably good.

The Subaru Forester with automatic transmission starts at $24,045. The EPA rates its fuel economy at 24 miles-per-gallon in the city and 32 miles-per-gallon on the highway.

In the end, the Subaru Forester could be a great car with three simple fixes:

  1. An acceptable infotainment system. Without this, the car is a failure.
  2. A steering wheel that doesn't feel cheap or plastic. (Just copy Volkswagen.)
  3. A better driver's seat. (Copy Volkswagen on this point as well, please.)

Overall, the Forester has a lot of potential that could be unlocked if these three execution misses can be fixed. 

This article is commentary by an independent contributor. At the time of publication, the author held AAPL and was short TSLA.