(comments are sorted latest first)

Steve from the UK adds,

Having just discovered this site, I am reading with interest your debate on the debacle of overtaking in F1. Anthony from America, with all due respect, if you know anything about the Formula 1 circus, you would realise that the chances of 10 more (or 15/20 as you suggest) cars joining the grid is.... well - snow balls chance in hell comes to mind. The startup costs for a Formula 1 team come to between 100 and 200 million dollars, and without some sort of manufacturer involvement, this is unachievable for any individual or private company, since the payback on this investment is not really forthcoming. Your looking at 5 or more teams joining, and with the track record of teams in recent years such as Pacific, and current teams financial difficulties ( Minardi, Prost, no-one wants to make this sort of commitment. Instead they're all waiting to see if Toyota falls on it's arse or can make a go of it. And lets face it, with almost an unlimited budget, and the vast experience of rallying and automotive building, if they can't, then it doesn't bode well for anyone else. 
However, maybe you do have a point. maybe the stakes are just too high now - the game too exclusive. maybe it is time to limit the teams in what they do and the resources they have to do it with, in an effort to make it easier to enter the formula in the first place. Downside is that it waters down the formula to such an extent that it is no longer what it is meant to be - i.e the technical pinnacle of worldwide motorsport.
For this reason I'm against this idea. As much as the next guy I would love for the kind of racing that was apparent in the 60's and 70's, with Jackie Stewart, Phil Hill, and Gilles Villeneuve for example. However, the sport has moved on now - in line with the modern world it is all about the micro chips as much as the drivers ability. But it should still be pushing the boundaries, just as it always has been. Therefore, I'll stick my neck on the line and adopt a controversial viewpoint. Stick with the technology and give the drivers and cars even more. What about driver adjustable wings? adaptive suspension to be reintroduced. 6 wheels - front or back - wings? where would you like them? To make this possible would probably mean the setting up of a two division F1. Unfortunately only the top teams ( or those most adept to getting sponsorship/building things on the cheap) would be able to get the best stuff. But it would filter down to the other teams eventually. the added bonus would be that some teams would get faster, and other teams not as quick, therefore more backmarkers, more overtaking........... Two class racing has been shown to great effect on the 2001 BTCC events. Especially the round where the top class cars start a lap down on the the lower class machines. Now there's an idea.....

Heretic's reply:

Dear Steve,

I absolutely agree that there are just not enough motor manufacturers left, with deep enough pockets, to make the addition of another 5 teams possible. Add to that the requirement that they should have the ability to become competitive within a reasonable timeframe (as opposed to fighting for last with the likes of Minardi) and it could not even apply to three teams.

However, I do not share your confidence in Toyota’s ability to adapt to F1 quickly. Off hand, in recent times, Ferrari are the only other team that I can think of that has been successful with a car that was totally built in-house and it took a long time before they had both the pace and the reliability to win.

I am sure that Toyota with all their money will get there but if I was a betting man I would not put money on their first two years. If they make it in their third year it will already be one hell of an achievement.

Accepting that F1 is the forefront of technological development is from a philosophical point of view very valid. In theory we should allow them to use all and every aspect to go faster.

Practically, I am not sure that it would work. The speed differential between the “haves” and “have nots” may become so extreme that it could reduce the teams and cars that compete (remember it was not so long ago that the slowest cars could only qualify for some of the races) and make overtaking back markers even more disruptive.

Speed, and corresponding danger to all concerned, is the only concern but that is a subject for another debate.

Anthony from the USA suggests

I don't have the time to read the extensive technical treatises such as the one above on the car-related barriers to overtaking in F1 today. However, while watching the latter part of the US GP from the stands at Indianapolis, noting the lack of passing and the yawning of the spectator next to me, I had one persistent thought: the tedium before me might be improved very simply by the addition of not less than 10 cars to the starting grid. The currently small number of starters allows the cars to put an excessive amount of space between one another, even before attrition begins. If there were a third again more competitors, they would unavoidably encounter one another more often. The law of averages would simply not allow a driver to proceed very long without pulling up to a car one position ahead or falling back to within range of a car behind. Battling groups would more easily form, and even among evenly matched competitors inevitable small driver errors would more often result in position changes. Observe how in NASCAR racing, when a driver in a battling group makes an error, it can cost him as much as ten positions in a matter of seconds. 

I don't know the barriers to implementing the foregoing; I imagine that they are major. However, I think "the more the merrier" is an approach with great promise, and if the will is there the problems, whether political or mechanical, will be solved and the expansion of the grids will just happen.

The Heretic didn't respond quickly enough so Anthony sent another email and said:

Are you sincere about wanting a radical solution? I'm suspicious. I've submitted this suggestion before, and it was ignored: you don't even list it in your "official roster" of solutions. I'll submit it again: A minimum of 10 more cars on the grid. Maybe 15 more; maybe 20. Aerodynamics be damned, there'd be more overtaking.

I can hear the whimpering and whining now: "Too dangerous!" Please. Grow up. This is auto racing. Besides, due to super-strong carbon fiber chassis and other safety improvements, decades pass between injurious or fatal accidents nowadays. I cannot understand resistance to this proposal on any basis other than cheap self-interest politics. Bottom line: each team DOESN'T WANT it's drivers to be overtaken!