In a new 3-Series you can turn the steering wheel with your index finger, there is no manual transmission, you hear fake engine noise.
The 15 year old car offers a completely different driving experience and he might prefer it over the bland, comfortable new car.
I'd be curious to see the numbers, but I'm pretty sure the new one has more oomph than the old one. The comfortable aspect I get, but new BMWs have plenty of bite in them.
See those slim runflats? Runflats save space in the trunk for the spare, and them being slim means they are hard. So in order for the ride to be softer, the axle suspension changed, and much softer silentblocks are being used. The result is, that your drive doesn't feel like your car is sitting on rails, like E90 or E46 did, instead it is muddy and jelly.
Another disaster is the start-stop system. When warm, the needles in starter can break. Meaning, that you just went down from highway to the petrol station, refuelled, and you cannot start anymore. You are stuck there on the station.
E90 came with RFT tires and at least E92/E93 lack spare wheel well in the trunk. I dunno about E90, it might be an option there like it was in E60s (but it's very rare).
They didn't use electric steering thankfully. It went downhill starting E9x though, the materials used inside wear much quicker, the suspension and road feel is somehow less than E46 and the chasing of weight savings but increasing comfort through electronics and servos means the car is heavy still but you no longer get that satisfying door or bonnet thump like you did in E39/E38/E46, which were pinnacle of BMWs engineering IMO. Cabin noise insulation is also less than pre 2005, I assume because of weight savings. The post 2005 cars are so complicated that non-enthusiast ownership is most likely a bad experience.
Don't forget the styling. Every car looks like the exact same boring "bar of soap with wheels" today. There's a little variation in terms of grill and light clusters, but from a distance I can no longer tell the difference between any of the top 10 sedan or coupe models.
In a new 3-Series you can turn the steering wheel with your index finger, there is no manual transmission, you hear fake engine noise. The 15 year old car offers a completely different driving experience and he might prefer it over the bland, comfortable new car.