About half of the sales in europe are still gasoline engines. Mostly four cylinder engines and several manufacturers are today making turbocharged 1.4-2.5 liter engines in place of larger naturally aspiranted engines. Some are even using even smaller two and three cylinder engines. For 2012 european car manufacturers may not have a corporate average higher than 130 gCO2/km to avoid fines. For 2020, the yet not finalized limit is probably going to be to be 95 gCO2/km.
So with car manufacturer looking to market these small displacement, fuel efficient engines to the public, using a similar engine in F1 would suit their need well.
So, you think F1 is best served with using an engine formula that reflects what is happening in lower spec models, in the main, in Europe? Or be using the same basic configuration that will be common to many diffrent racing series?
To have an engine that produces a lot of vibrations and is difficult to package isn't not exactly what the chassis designers want even if it offers the lowest fuel consumption.
Ferrari apparently argued for a V6 because the chassis designers were not too keen on an L4.
Fuel restrictions came into effect in 1985 with a limit of 220 liters. This was reduced for 1986 to 195 liters. In 1987 a boost limit of 4.0 bar was introduced. Then in 1988 the boost limit was reduced to 2.5 bar and the fuel limit to 150 liters.
If we take the Honda RA168E which was used to win the 1988 championship it was a development of the RA163E introduced in 1983 before there were any limits. That was essentially the case for all engines, they were designed before the fuel restrictions came into effect.
If they are allowed more boost than in 1988 they will run to a slightly lower engine speed than they did back then. Probably about 20% less, which should translate into a peak power at about 10,000 rpm.
The point is Honda chose to stay with the V6, but they didn't have to.
The peak power will be less than 10,000, otherwise they'll find it really hard to use the slipstream to pass.