I had the first Twingo model with that engine. Sure, reliability was exceptional, and it also felt nice to drive for a low power engine (55 HP). What wasn't exceptional however was fuel economy, which significantly increased the total cost of ownership of a car like the Twingo.
I think the car made it to almost 300000 km with the engine showing barely any sign of wear. Some parts broke down, and there was still regular maintenance, which, combined with poor fuel economy and state subsidies made it not economically viable to keep the car even though it still ran. The newer model we bought later didn't last as long, the engine was good but not as robust, but it was still worth changing because of fuel economy alone.
At no point we considered environmental factors, only cost, but they are tied, since better fuel economy means both lower costs and lower emissions.
I think the car made it to almost 300000 km with the engine showing barely any sign of wear. Some parts broke down, and there was still regular maintenance, which, combined with poor fuel economy and state subsidies made it not economically viable to keep the car even though it still ran. The newer model we bought later didn't last as long, the engine was good but not as robust, but it was still worth changing because of fuel economy alone.
At no point we considered environmental factors, only cost, but they are tied, since better fuel economy means both lower costs and lower emissions.
So in the end, you we a engine that was reliable for sure but didn't meet modern standards in terms of running costs, emissions and performance. When the Twingo came out, the use of the Cléon-Fonte engine was generally considered a serious downside, and it was changed to the more modern and appropriate "Energy" engine shortly after.