The mouthy, overweight tycoon - who is also mayor of glitzy Marbella - is in deep trouble, accused of illegally funnelling at least 450m pesetas (pounds 2m) of Marbella's public funds to his club via faked contracts. It is the most spectacular of a slew of accusations that have been thrown athim since he became boss of the city eight years ago.
Atletico is Spain's only club sponsored by a town hall, and the name Marbella marches in huge letters across players' scarlet-and-white striped shirts. Gil always insisted that the publicity provided to his city by his club was free. But when the state's anti-corruption squad raided a company attached to Marbella town hall last November, they found documents which they claim show the city had been funding "Atleti" by up to pounds 1m a year.
The case was strong enough to send Gil to jail in January, which prompted Atletico to give away all the tickets for that week's match to encourage fans to show up in solidarity with their chairman. Thousands of supporters marched in Marbella: the blonde, the perma-tanned, the wearers of pastel leather jackets more at home in Hola! magazine than street protests, still less football matches.
Gil, 66, walked free within a week on payment of pounds 420,000 bail, pleading a heart condition. He has since toned down his usual foul language and loutish behaviour. But he created a stir last month when he was banned from accompanying his players to Rome for a Uefa Cup match. The judge declined his offer to pay for a police escort.
Police are also investigating the curious case of the Russian statue, "Victory", that sits in Marbella's yacht marina, supposedly a gift from the mayor of Moscow. Gil's local socialist opponents claim that ratepayers paid pounds 600,000 to the sculptor Zurab Tsereteli. They say a confusing trail of paperwork obscures the handover of pounds 130,000 in cash plus three luxury apartments.
Gil's increasingly eccentric political gestures have aroused criticism, too: he recently dragged from the town hall cellar a larger-than-life bronze bust of the former dictator Franco, a gift from Finland in 1967, and installed it in the foyer.
Then he fantasised about paying pounds 600,000 for a decommissioned aircraft carrier from the Falklands war to moor in the bay as a floating casino. It would mean dredging the bay.
Gil has been behind bars before. In 1969 the young property speculator was jailed for five years for criminal negligence after an apartment block he built in Segovia collapsed, killing 58. It had no plans, no architect and no surveyor, and the cement was barely dry. After 18 months, Franco pardoned him. He borrowed money and started again.
Marbella caught Gil's fancy 10 years later while he was staying in a weight-loss clinic. He homed in on property deals with such voracious contempt for planning laws that the socialist council declared him persona non grata. His way round that was to form his own party, the Independent Liberal Group (GIL), and stand for mayor in 1991. He won by a landslide.
He cracked down on street crime and promised to corral prostitutes in a purpose-built "whore-odrome". One August night he descended upon the harbourside with his bodyguards and started haranguing youngsters in the bars: "What a drink-sodden face you've got, sonny. How much have you spent on drugs today? You're dross and I'm going to get rid of you. Slugs!"
Several were injured and a police car burnt in scuffles.
Marbella's income comes mostly from the sale of land and fees for construction projects. Mayor Gil, the most prosperous property entrepreneur in town, earmarked green areas ravaged by forest fires for multi-storey blocks. He courted Middle Eastern, then Russian, millionaires who flocked to Marbella to fling new money into speculative development. Resident jetsetters gasped in horror as walls of concrete blocked their views of the Mediterranean.
His business deals prospered so dramatically that he recently claimed to have lost all respect for money because he had "too much". But now the city is millions of pounds in debt and the state prosecution service wants to know why. Atletico's fortunes may revive, but Gil's glory days could soon be over.