No offence taken. On the other hand, I have had several cars during my life with poor traction, wiggling and losing grip sideways easily. The Citroen C3 was one of them, a Volvo 340 from the early or mid 80's was another. In both of those cars, overtaking on motorways was a challenge, especially in crosswind, which we have a lot on the roads I need to travel almost every day. Both of those were weak, tall, short and not well balanced, with pretty high center of gravity. Jost google "moose test" or "elk test" and you will find plenty small cars losing grip, including the brand new Rav 4, ever since 1997 when the Swedish magazine Teknikens Värld managed to turn over a Mercedes A class car and forced Mercedes to seriously improve the car stability. Spinning wheels is also not something unknown for small and weak cars, even though today we have a lot of smart solutions to prevent that as much as possible. Horse power doesn't matter, except that high powered cars may (or may not) lose grip easier, but at a certain point, every car will lose grip. Of course, it is possible to build a car which would never lose grip but those will be heavy and slow, or must have some other serious limitations.
OK, if you think 100kg more does not make a difference that's fine, but never the less, my point was that to answer your question, "just wondering how much quicker the 40 is". You should notice the difference because the difference in acceleration is a measurable fact, and 3.9s difference for 0-100kmh is HUGE. While I have no data, the difference should be obviously notable even if you measure from 50kmh to 100kmh or 70kmh to 120kmh.